Immunomodulative effect of cholera toxin in mice

Biotechnology Letters, 2008

The bacterial superantigen staphylococcal enterotoxin B (SEB) is a potent inducer of cytotoxic T-cell activity and cytokine production in vivo. We investigated the possibility of the therapeutic application of SEB in patients with fibrosarcoma. The anti-tumor effect of SEB in mice with inoculated fibrosarcoma (WEHI-164) was examined by intravenous (IV) and intratumoral (IT) injection and the sizes of the inoculated tumors, IFN-γ production, and CD4+/CD8+ T cell infiltration were determined. The inoculated tumors were also examined histologically. In the mice in the IV-injected group, a significant reduction (P < 0.02) of tumor size was observed in comparison with mice in the IT-injected and control groups. Furthermore, the mice in the IV-injected group showed significantly higher levels of IFN-γ (P < 0.009) and CD4+/CD8+ T cell infiltration when compared with the other groups (P < 0.02). A significantly higher frequency of necrosis in tumor tissues was also observed in mice in the IV-injected group (P < 0.05). Our present findings suggest that tumor cell death is caused by increased cytotoxic T-cell activity and cytokine levels in response to the IV injection of SEB and that SEB may be a good option for use as a novel therapy in patients with fibrosarcoma.

Journal of Cellular Biochemistry, 1988

One hour of exposurc to cholera toxin is sufficient to elicit a significant delay in the initiation of DNA synthesis and cell division in lactogenic hormone-dependent Nb2-1 1C lymphoma cells. The inhibitory effect occurs already at very low concentrations of cholera toxin (5-50 fM), at which it is not accompanied by a detectable increase in intracellular CAMP. or ADP-ribosylation of the alpha subunit of G,. thc stimulatory guaninc nucleotide binding protein of adenylate cyclase; IBMX, the phosphodiesterase inhibitor. acts synergistically to cholera toxin, indicating that a minute increase in CAMP may be sufficient for the inhibition. This indication is substantiated by the finding that dibutyryl cAMP also inhibits cell proliferation. Phorbol diester reverses partially the inhibitory activity of cholera toxin. It is most likely that this effect does not result from blocking the increase in CAMP. but rather from some subsequent. yet unidentified. events. The inhibitory effect of cholera toxin is not dependept on the concentration of the proliferation-stimulating lactogenic hormone and cannot be abolished or reduced by excess of the hormone. Cholera toxin also inhibits the autonomous proliferation of a lactogenic hormone-independent cell line (Nb2-SP); however, in this case the inhibition is not affected by TPA.

Proceedings of the National Academy of Sciences, 2004

When spores of the anaerobic bacterium Clostridium novyi-NT are systemically injected into animals, they germinate exclusively within the hypoxic regions of cancers. The germinated bacteria destroy adjacent tumor cells but spare a rim of well oxygenated tumor cells that subsequently expand. Surprisingly, we found that Ϸ30% of mice treated with such spores were cured of their cancers despite the viable tumor rim initially remaining after spore germination. The mechanism underlying this effect was shown to be immune-mediated, because cured animals rejected a subsequent challenge of the same tumor. Similar effects were observed in rabbits with intrahepatic tumors. It was particularly notable that the induced immune response, when combined with the bacteriolytic effects of C. novyi-NT, could eradicate large established tumors.

PubMed, 1989

A mouse IgG2b anti-pan carcinoma monoclonal antibody, NR-LU-10, was shown to bind homogeneously to ascites xenografts of both ovarian and colon carcinoma. Following linkage to a highly potent holotoxin, Pseudomonas exotoxin A (PE), NR-LU-10 demonstrated high potency and selectivity in vitro (ID50 = 100 pg/ml; elimination of greater than or equal to 4.5 logs of cells). The conjugate was evaluated for therapeutic efficacy against a human colon tumor (HT-29) transplantable in the peritoneal cavity of nude mice. Beginning 3 days after HT-29 injection, mice received either three or six i.p. injections of 0.5 micrograms of unconjugated NR-LU-10 or immunotoxin conjugate (NR-LU-10/PE) every other day. Mice that received three or six treatments of NR-LU-10 alone had median survival times (MSTs) of 39 and 40 days, respectively, which did not differ significantly from the MST observed for the untreated control groups (MST = 35 days). In contrast, treatment with three or six injections of 0.5 micrograms NR-LU-10/PE exhibited significantly increased MSTs (P = 0.002) of 50 and 60 days, respectively. Coinjection of unconjugated NR-LU-10 (20 micrograms) and 0.5 micrograms of NR-LU-10/PE blocked the therapeutic effect of the immunotoxin (MST = 33 days). The therapeutic efficacy of NR-LU-10/PE was further enhanced against HT-29 when administered i.p. during and after cytoreductive chemotherapy. The i.p. administration of 300 mg/lg of cyclophosphamide plus 100 mg/kg of the chemoprotective drug, WR-2721, 10 and 17 days posttumor cell inoculation induced a significant increase in MST from 36 days to 59 days (P = 0.002). Interestingly, groups of mice that received either two, four, or seven treatments of NR-LU-10/PE following cytoreductive therapy exhibited a further significant increase (P = 0.001) in MSTs of 89, 97, and 105 days, respectively. Therefore, the use of immunotoxin therapy following cytoreductive chemotherapy significantly prolonged survival time of mice bearing the HT-29 colon tumor over that observed with chemotherapy or NR-LU-10/PE alone.

Human studies and clues from animal models have provided important links between gastrointestinal (GI) tract bacteria and colon cancer. Gut microbiota antigenic stimuli play an important role in shaping the intestinal immune responses. Therefore, especially in the case of inflammation-associated colon cancer, gut bacteria antigens may affect tumorigenesis. The present study aimed to investigate the effects of the oral administration of a bacterial product with known immunomodulatory properties on inflammation-driven colorectal neoplasmatogenesis. For that, we used cholera-toxin and a well-established mouse model of colon cancer in which neoplasia is initiated by a single dose of the genotoxic agent azoxymethane (AOM) and subsequently promoted by inflammation caused by the colitogenic substance dextran sodium sulfate (DSS). We found that a single, low, non-pathogenic dose of CT, given orally at the beginning of each DSS treatment cycle downregulated neutrophils and upregulated regulatory T-cells and IL-10 in the colonic mucosa. The CT-induced disruption of the tumorpromoting character of DSS-induced inflammation led to the reduction of the AOM-initiated colonic polypoidogenesis. This result adds value to the emerging notion that certain GI tract bacteria or their products affect the immune system and render the microenvironment of preneoplastic lesions less favorable for promoting their evolution to cancer.

Journal of Clinical Investigation, 1990

Introduction Cholera toxin (CT) inhibited the in vitro growth of three of four human small-cell lung carcinoma (SCLC) cell lines with a 50% inhibitory concentration of 27-242 ng/ml. Loss of surface membrane ruffling and the capacity of [Tyr4J-bombesin, vasopressin, and fetal calf serum to stimulate increases in intracellular free calcium clearly preceded effects on cellular metabolic activity and cell growth. 25 1-[Tyr4j-bombesin binding was unaffected by CT treatment but [Tyr41-bombesin stimulated phospholipase C activity was decreased in membranes from CU-treated SCLC cells. Cl stimulated a rapid but transient increase in intracellular cyclic AMP (IcAMPI;) in SCLC. The effects of Cl on susceptible SCLC were not reproduced by elevations of IcAMPi; induced by forskolin or cyclic AMP analogues. GM, ganglioside, the cellular binding site for CT, was highly expressed in the CT-sensitive but not the Cl-resistant SCLC cell lines. In contrast, expression of guanine nucleotide binding protein substrates for ADP-ribosylation by CT was similar. These data demonstrate the existence of a CT-sensitive growth inhibitory pathway in SCLC-bearing GM, ganglioside. Addition of CT results in decreased responsiveness to several mitogenic stimuli. These results suggest novel therapeutic approaches to human SCLC.

European Journal of Immunology, 2004

We previously demonstrated that cholera toxin (CT) is highly efficient as a combined carrier and adjuvant for dendritic cell (DC) vaccination, inducing strong Th1-dominated B cell and CD4 + T cell responses. In this study we show that vaccination with DC pre-pulsed ex vivo with CT-conjugated OVA (OVA-CT) gives rise to OVA-specific CD8 + T cells that produce IFN-+ and are cytotoxic for OVA-expressing E.G7 tumor cells both in vitro and in vivo. The induction of specific CD8 + CTL by OVA-CT-treated DC was associated with enhanced presentation of OVA peptide (SIINFEKL) on MHC class I in combination with an overall activation of the pulsed DC. Vaccination of mice with OVA-CT-pulsed DC resulted in rejection of already established MHC class I-positive, MHC class II-negative, OVA-expressing E.G7 tumors in an antigen-specific, CD8 + T cell-dependent fashion and was associated with high numbers of tumor-infiltrating CD8 + T cells. Conjugation of antigen to CT facilitated DC uptake of the linked antigen through the GM1 receptor-binding B subunit and induced strong activationmaturation signals through the biologically active A subunit. These results have interesting implications for DC vaccination aimed at inducing CTL immune responses. Abbreviations: CT: Cholera toxin CTB: Cholera toxin B subunit OVA-CT: CT-conjugated OVA OVA-CTB: CTBconjugated OVA PGE2: Prostaglandin E2 1272 K. Eriksson et al.

Experimental Cell Research, 1976

Freeze fracture studies have been performed on a murine lymphoblastid cell line treated with cholera toxin. A significant increase in intramembranous particles (IMP) present on the B fracture face was observed for cells incubated with 10 pg/ml cholera toxin for 3 h, as compared with control cells or cells incubated with 10 nglml toxin. Cholera toxin at 10 rig/ml causes elevation in levels of intracellular CAMP. This change in IMP was no longer present after 24 h incubation. The observed increase in the number of IMP on the B fracture face demonstrates an alteration of membrane components by cholera toxin.

Academia Quantum, 2024

This article reviews the history of J. von Neumann’s analysis of hidden variables in quantum mechanics and the subsequent analysis by others. In his book The Mathematical Foundations of Quantum Mechanics, published in 1932, von Neumann performed an analysis of the consequences of introducing hidden parameters (hidden variables) into quantum mechanics. He arrived at two principal conclusions: first, hidden variables cannot be incorporated into the existing theory of quantum mechanics without major modifications, and second, if they did exist, the theory would have already failed in situations where it has been successfully applied. This analysis has been taken as an “incorrect proof” against the existence of hidden variables, possibly due to a mistranslation of the German word prufen. von Neumann’s so-called proof isn’t even wrong as such a proof does not exist, but it is an examination of the limitations imposed by internal consistency of the Hilbert space formulation of the theory. One of the earliest attempts to eliminate uncertainty, by D. Bohm, requires a major modification of quantum mechanics (observables are not represented by Hermitian operators), which supports von Neumann’s first principal conclusion. However, testing the Bohm theory requires constructing a physically impossible initial state. As such, the theory has no experimental consequences, so W. Pauli referred to it as an “uncashable check”. As there are no observable consequences, the Bohm theory is possibly a counterexample to von Neumann’s second conclusion that hidden variables in particular would have already led to a failure of the theory.