High incidence of neoplasms in female NZB/NZW mice treated with pulse doses of cyclophosphamide

The immunosuppressive properties of cyclophosphamide prevent formation of anti-DNA antibodies and prolong lifespans in autoimmune NZB/NZW mice, an animal model of systemic lupus erythematosus. In the current study, NZB/NZW mice were treated with weekly doses of cyclophosphamide to determine if intermittent pulses of the drug were effective therapy. Life-long treatment with cyclophosphamide, 56 mg/kg/week, was started at the mean age of 6 weeks; results were compared with saline-injected control mice. Pulse therapy with cyclophosphamide suppressed anti-DNA antibody levels, prevented severe qlomerulonephritis and prolonged longevity. Seventeen of 19 treated mice developed neoplasms; 7 of these immunosuppressed animals had 2 to 4 separate neoplasms. Examination of earlier studies in this laboratory in which NZB/NZW mice were treated each day with cyclophosphamide showed that daily and weekly therapeutic regimens had similar immunosuppressive and oncogenic effects.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25065/1/0000496.pd

Administration of either anti-CD40 or interleukin-12 following lethal total body irradiation induces acute lethal toxicity affecting the gut

AbstractInterleukin (IL)-12 and antibodies against CD40 have demonstrated antitumor effects in a variety of in vivo model systems. However, both agents can also mediate significant toxicities either when used following lethal TBI or when administered in combination with other agents such as IL-2. In this study, we assessed the effects of anti-CD40 monoclonal antibody (MoAb) and IL-12 in lethally irradiated mice. Acute lethal toxicity was observed following the administration of either 10 microg anti-CD40 MoAb (FGK45) or 0.5 microg of recombinant murine (rm)IL-12 that resulted in 100% mortality of all mice within 4 to 6 days. Histological evaluation revealed destruction of the normal gut architecture in both anti-CD40 MoAb- and rmIL-12-treated mice. Analysis of serum cytokine levels in the lethally irradiated mice receiving anti-CD40 MoAb demonstrated a marked increase of interferon (IFN)-gamma and IL-12 p40, whereas mice receiving rmIL-12 demonstrated a marked increase of IFN-gamma. Lethally irradiated IL-12 p40 knock-out mice were resistant to anti-CD40-induced toxicity, suggesting that the lack of IL-12 p40 with no possibility of making functional IL- 12 p70 is key for this toxic reaction. Similarly, lethally irradiated IFN-gamma knock-out mice were completely resistant to rmIL-12-induced toxicity, suggesting that IFN-gamma is a major player in IL-12-mediated toxicity. These results suggest that both anti-CD40 MoAb and rmIL-12 induce an acute fatal toxicity characterized by similar intestinal pathology and mediated in part by IFN-gamma.Biol Blood Marrow Transplant 2002;8(6):316-25

Melanoma induction by ultraviolet A but not ultraviolet B radiation requires melanin pigment

Malignant melanoma of the skin (CMM) is associated with ultraviolet radiation exposure, but the mechanisms and even the wavelengths responsible are unclear. Here we use a mammalian model to investigate melanoma formed in response to precise spectrally defined ultraviolet wavelengths and biologically relevant doses. We show that melanoma induction by ultraviolet A (320–400 nm) requires the presence of melanin pigment and is associated with oxidative DNA damage within melanocytes. In contrast, ultraviolet B radiation (280–320 nm) initiates melanoma in a pigment-independent manner associated with direct ultraviolet B DNA damage. Thus, we identified two ultraviolet wavelength-dependent pathways for the induction of CMM and describe an unexpected and significant role for melanin within the melanocyte in melanomagenesis

Specific Excision of the Selenocysteine tRNA\u3csup\u3e [Ser]Sec\u3c/sup\u3e (\u3ci\u3eTrsp\u3c/i\u3e) Gene in Mouse Liver Demonstrates an Essential Role of Selenoproteins in Liver Function

Selenium is essential in mammalian embryonic development. However, in adults, selenoprotein levels in several organs including liver can be substantially reduced by selenium deficiency without any apparent change in phenotype. To address the role of selenoproteins in liver function, mice homozygous for a floxed allele encoding the selenocysteine (Sec) tRNA [Ser]Sec gene were crossed with transgenic mice carrying the Cre recombinase under the control of the albumin promoter that expresses the recombinase specifically in liver. Recombination was nearly complete in mice 3 weeks of age, whereas liver selenoprotein synthesis was virtually absent, which correlated with the loss of Sec tRNA [Ser]Sec and activities of major selenoproteins. Total liver selenium was dramatically decreased, whereas levels of low molecular weight selenocompounds were little affected. Plasma selenoprotein P levels were reduced by about 75%, suggesting that selenoprotein P is primarily exported from the liver. Glutathione S-transferase levels were elevated in the selenoprotein-deficient liver, suggesting a compensatory activation of this detoxification program. Mice appeared normal until about 24 h before death. Most animals died between 1 and 3 months of age. Death appeared to be due to severe hepatocellular degeneration and necrosis with concomitant necrosis of peritoneal and retroperitoneal fat. These studies revealed an essential role of selenoproteins in liver function

Molecular analysis reveals heterogeneity of mouse mammary tumors conditionally mutant for Brca1

<p>Abstract</p> <p>Background</p> <p>Development of therapies for patients with BRCA1 mutations has been hampered by lack of readily available <it>in vitro </it>and <it>in vivo </it>models. We recently showed that transplantation of transgenic mammary tumors as cell suspensions into naïve recipients generates reproducible tumors with remarkable stability of gene expression profile. We examined the expression profiles of original and serially transplanted mammary tumors from <it>Brca1 </it>deficient mice, and tumor derived cell lines to validate their use for preclinical testing and studies of tumor biology.</p> <p>Methods</p> <p>Original tumors, serially transplanted and multiple cell lines derived from <it>Brca1 </it>mammary tumors were characterized by morphology, gene and protein expression, and cell surface markers.</p> <p>Results</p> <p>Gene expression among <it>Brca1 </it>tumors showed more heterogeneity than among previously characterized tumors from MMTV-<it>PyMT </it>and -<it>Wnt1 </it>models. Gene expression data segregated <it>Brca1 </it>tumors into 3 distinct types: basal, mixed luminal, and tumors with epithelial-to-mesenchymal transition (EMT). Serial transplantation of individual tumors and multiple cell lines derived from the original tumors recapitulated the molecular characteristics of each tumor of origin. One tumor had distinct features of EMT and gave rise to cell lines that contained a distinct CD44⁺/CD24^-/lowpopulation that may correlate with human breast cancer stem cells.</p> <p>Conclusion</p> <p>Although individual tumors expanded by transplantation maintain the genomic profile of the original tumors, the heterogeneity among <it>Brca1 </it>tumors limits the extent of their use for preclinical testing. However, cell lines offer a robust material for understanding tumor biology and response to therapies driven by BRCA1 deficiency.</p

Toxicity of polybrominated biphenyls (Firemaster BP-6) in rodents

Pregnant rodents were fed concentrations of a mixture of polybrominated biphenyls (Firemaster BP-6) during the pregnancy. The material appears to be weakly teratogenic, causing exencephaly and cleft palate in mice. Decreasing birth weight with increasing dosage of the material was seen in both mice and rats. Nonpregnant mice fed 1000 ppm Firemaster BP-6 for 11 days had a marked increase in liver size and weight.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21936/1/0000343.pd

Immunologic and Hematopoietic Effects of CD40 Stimulation after Syngeneic Bone Marrow Transplantation in Mice

CD40 is a molecule present on multiple cell types including B lymphocyte lineage cells. CD40 has been shown to play an important role in B cell differentiation and activation in vitro, although little is known concerning the effects of CD40 stimulation in vivo. We therefore examined the effects of CD40 stimulation in mice using a syngeneic bone marrow transplantation (BMT) model in an effort to augment B cell recovery after high dose therapy with hematopoietic reconstitution. After the BMT, mice were treated with or without 2-6 μg of a soluble recombinant murine CD40 ligand (srmCD40L) given intraperitoneally twice a week. A significant increase in B cell progenitors (B220 +/surface IgM -) was observed in the bone marrow of mice receiving the srmCD40L. The treated recipients also demonstrated improved B-cell function with increases in total serum immunoglobulin and increased splenic mitogen responsiveness to LPS being noted. Additionally, srmCD40L treatment promoted secondary lymphoid organ repopulation, accelerating germinal center formation in the lymph nodes. Total B cell numbers in the periphery were not significantly affected even with continuous srmCD40L administration. Lymphocytes obtained from mice treated with the ligand also had increases in T cell mitogen and anti-CD3 mAb responsiveness and acquired the capability to produce IL-4. Surprisingly, treatment with srmCD40L also produced hematopoietic effects in mice, resulting in an increase of BM and splenic hematopoietic progenitor cells in the mice after BMT. Treatment with srmCD40L significantly increased granulocyte and platelet recovery in the peripheral blood. Incubation of BMC with srmCD40L in vitro also resulted in increased progenitor proliferation, demonstrating that the hematopoietic effects of the ligand may be direct. Thus, stimulation of CD40 by its ligand may he beneficial in accelerating both immune and hematopoietic recovery in the setting of bone marrow transplantation

Oral delivery of il-27 recombinant bacteria attenuates immune colitis in mice

BACKGROUND & AIMS: Treatment of inflammatory bowel disease (IBD) would benefit from specific targeting of therapeutics to the intestine. We developed a strategy for localized delivery of the immunosuppressive cytokine IL27, which is actively synthesized in situ by the food-grade bacterium Lactococcuslactis (LL-IL-27), and tested its ability to reduce colitis in mice. METHODS: The 2 genes encoding mouse IL27 were synthesized with optimal codon usage for L lactis and joined with a linker; a signal sequence was added to allow for secretion of the product. The construct was introduced into L lactis. Colitis was induced via transfer of CD4(+)CD45RB(hi) T cells into Rag(−/−) mice to induce colitis; 7.5 weeks later, LL-IL-27 was administered to mice via gavage. Intestinal tissues were collected and analyzed. RESULTS: LL-IL-27 administration protected mice from T-cell transfer-induced enterocolitis and death. LL-IL-27 reduced disease activity scores, pathology features of large and small bowel, and levels of inflammatory cytokines in colonic tissue. LL-IL-27 also reduced numbers of CD4(+) and IL17(+) T cells in gut-associated lymphoid tissue. The effects of LL-IL-27 required production of IL10 by the transferred T cells. LL-IL-27 was more effective than either LL-IL-10 or systemic administration of recombinant IL27 in reducing colitis in mice. LL-IL-27 also reduced colitis in mice following administration of dextran sodium sulfate. CONCLUSIONS: L lactis engineered to express IL27 (LL-IL-27) reduces colitis in mice, by increasing production of IL10. Mucosal delivery of LL-IL-27 could be a more effective and safer therapy for IBD

Selenium and Selenoprotein Deficiencies Induce Widespread Pyogranuloma Formation in Mice, while High Levels of Dietary Selenium Decrease Liver Tumor Size Driven by TGFα

Changes in dietary selenium and selenoprotein status may influence both anti- and pro-cancer pathways, making the outcome of interventions different from one study to another. To characterize such outcomes in a defined setting, we undertook a controlled hepatocarcinogenesis study involving varying levels of dietary selenium and altered selenoprotein status using mice carrying a mutant (A37G) selenocysteine tRNA transgene ($Trsp^{tG37}$) and/or a cancer driver TGFα transgene. The use of $Trsp^{tG37}$ altered selenoprotein expression in a selenoprotein and tissue specific manner and, at sufficient dietary selenium levels, separate the effect of diet and selenoprotein status. Mice were maintained on diets deficient in selenium (0.02 ppm selenium) or supplemented with 0.1, 0.4 or 2.25 ppm selenium or 30 ppm triphenylselenonium chloride (TPSC), a non-metabolized selenium compound. $Trsp^{tG37}$ transgenic and TGFα/$Trsp^{tG37}$ bi-transgenic mice subjected to selenium-deficient or TPSC diets developed a neurological phenotype associated with early morbidity and mortality prior to hepatocarcinoma development. Pathology analyses revealed widespread disseminated pyogranulomatous inflammation. Pyogranulomas occurred in liver, lungs, heart, spleen, small and large intestine, and mesenteric lymph nodes in these transgenic and bi-transgenic mice. The incidence of liver tumors was significantly increased in mice carrying the TGFα transgene, while dietary selenium and selenoprotein status did not affect tumor number and multiplicity. However, adenoma and carcinoma size and area were smaller in TGFα transgenic mice that were fed 0.4 and 2.25 versus 0.1 ppm of selenium. Thus, selenium and selenoprotein deficiencies led to widespread pyogranuloma formation, while high selenium levels inhibited the size of TGFα–induced liver tumors