Cultivation,characterization and modulation of rat thymic nonlymphoid cells in vitro

Thymic fragments of young adult rats were cultivated in vitro using an explant technique. Two weeks later, non-lymphoid cells were characterized by enzyme-cytochemistry and immuno-cytochemistry. Based on cytomorphological criteria and cell-specific markers approximately 95% of cells were classified into 3 main types: epithelial cells, macrophages and fibroblasts. The effect of dexamethasone and amphotericin B, known modulators of cell growth in culture was also studied. Quantitative analysis showed that amphotericin B inhibited proliferation of macrophages and epithelial cells, while dexamethasone suppressed proliferation of fibroblasts and promoted growth of epithelial cells.Abbreviations TNLC Thymic Non-Lymphoid Cells - NSE Non-Specific Esterase     

Egr family members regulate nonlymphoid expression of Fas ligand, TRAIL, and tumor necrosis factor during immune responses

The Fas ligand (FasL)/Fas pathway is crucial for homeostasis of the immune system and peripheral tolerance. Peripheral lymphocyte deletion involves FasL/Fas in at least two ways: coexpression of both Fas and its ligand on T cells, leading to activation-induced cell death, and expression of FasL by nonlymphoid cells, such as intestinal epithelial cells (IEC), that kill Fas-positive T cells. We demonstrate here that superantigen Staphylococcus enterotoxin B (SEB) induced a dramatic upregulation of FasL, TRAIL, and TNF mRNA expression and function in IEC from BALB/c and C57BL/6 mice. Using adoptive transfer in which CD4(+) T cells from OT-2 T-cell receptor transgenic mice were transferred into recipients, we observed an induction in IEC of FasL, TRAIL, and TNF mRNA after administration of antigen. Specific Egr-binding sites have been identified in the 5' promoter region of the FasL gene, and Egr-1, Egr-2, and Egr-3 mRNA in IEC from mice treated with SEB and from transgenic OT-2 mice after administration of antigen was upregulated. Overexpression of Egr-2 and Egr-3 induced endogenous ligand upregulation that was inhibited by overexpression of Egr-specific inhibitor Nab1. These results support a role for Egr family members in nonlymphoid expression of FasL, TRAIL, and TNF.     

Dihydroartemisinin shift the immune response towards Th1, inhibit the tumor growth in vitro and in vivo

Some investigators have been found that Artemisinin and its derivates have inhibitory effect on growth of cancer cells. Among these derivatives, Dihydroartemisinin (DHA) is well known as a semi-synthetic one. In addition, T cells are proved to be essential for the destruction of cancer cells. In this research, we assessed the effects of DHA on tumor cell growth inhibition in vitro by MTT assay and in vivo by intra tumor injection of DHA against breast cancer. The results showed that the IC₅₀ values of DHA for RIN pancreatic tumor cell line were 30 μM and significant decrease in the tumor size in vivo. Also we evaluate the effect of DHA on the modulation of immune response in tumor bearing animals; these include the splenocyte proliferation using the BrdU kit; measurement of cytokine profile by ELISA, and evaluate the percentage of T regulatory cells in the spleen by flowcytometry. Our results demonstrated that a significant decrease in the level of IL-4 in the animals treated with DHA and significant decreased in the level of splenic CD4⁺CD25⁺ Foxp3⁺ T regulatory cells.     

Characterization in vitro and in vivo of hammerhead ribozymes directed against murine tumor necrosis factoralpha.

A hammerhead ribozyme directed against murine TNFalpha (mTNFalpha) mRNA has been constructed. In vitro studies showed that this ribozyme was released from the parent molecule by flanking cis-acting hammerhead and hairpin ribozymes. This same anti-mTNFalpha ribozyme specifically cleaved both synthetically derived substrate RNA and mTNFalpha mRNA within a pool of total cellular RNA. Endogenous delivery of this anti-mTNFalpha ribozyme via the self-cleaving cassette reduced mTNFalpha mRNA and protein levels in lipopolysaccharide (LPS)-stimulated, stably transfected murine macrophage RAW 264.7 cells. When complexed to liposomes and exogenously delivered to mouse peritoneal macrophages, the same ribozyme, with and without the cis-acting ribozymes, reduced mTNFalpha protein levels. However, an irrelevant ribozyme delivered in an identical fashion was also effective at reducing mTNFalpha protein levels. These data suggest that anti-mTNFalpha ribozymes can be constructed which efficiently cleave mTNFalpha mRNA, but irrelevant RNA/liposome complexes also effectively limit TNFalpha mRNA expression and can mimic functional ribozyme activity under in vitro conditions.     

Analysis of protective and cytotoxic immune responses in vivo against metabolically inactivated and untreated cells of a mutagenized tumor line (requirements for tumor immunogenicity)

The immunogenicity of a mutagenized subline (ESb-D) of the weakly immunogenic T-cell lymphoma L 5178 Y ESb has been characterized. The injection of 10(6) ESb-D cells ip did not establish lethal tumors in untreated DBA/2 mice but established tumors in sublethally irradiated mice. Injection of ESb-D cells into otherwise untreated DBA/2 mice established also a state of protective immunity against the subsequent injection of otherwise lethal doses of ESb tumor cells. Protection was only obtained after injection of intact but not UV-irradiated or mitomycin-C-treated ESb-D cells. A direct T-cell-mediated cytotoxic activity was also demonstrable in the spleen cells of DBA/2 mice after injection of ESb-D cells but not ESb cells. The cytotoxic activity was variant specific for ESb-D target cells, and it was induced only with intact but not UV-irradiated or mitomycin C-treated ESb-D cells. This suggested that the induction of protective and cytotoxic immunity may require the persistence of the antigen or unusually high antigen doses. The in vivo priming for a secondary in vitro cytotoxic response, in contrast, was achieved with intact and also with mitomycin C-treated ESb-D cells but again not with UV-irradiated ESb-D cells. This indicated that the metabolic activity was a minimal requirement for the in vivo immunogenicity of the ESb-D tumor line. The secondary cytotoxic activity was demonstrable on ESb-D and ESb target cells and could be restimulated in vitro about equally well with ESb-D and ESb cells. But the in vivo priming was again only obtained with ESb-D cells and not with ESb cells. These experiments thus demonstrated that the requirements for immunogenicity are more stringent in vivo than in vitro, and more stringent for the induction of direct cytotoxic and protective immunity in vivo than for the in vivo priming for secondary in vitro responses.     

In vivo activity of lymphokine-activated macrophages in host defense against neoplasia

Purified splenic macrophage (M phi) from normal DBA/2J mice and mice bearing P815 tumors were examined for responsiveness to lymphokine (LK) preparations containing high concentrations of IFN-gamma. For both normal and tumor-bearing M phi, LK treatment induced morphologic changes and increased the percentage of Ia+ cells from 35 to 55%. Although neither population exhibited spontaneous cytotoxicity toward P815 targets, LK treatment induced considerable tumoricidal activity in tumor-bearing M phi (32 to 80% lysis) but only minimal activity in normal M phi (8 to 17% lysis). Subcutaneous injection of 1 X 10(6)P815 cells into DBA/2J led to progressive tumor growth and death of 100% of the recipients after 27 +/- 3 days. Injection of a 1:18 mixture of P815 with either LK-activated normal or tumor-bearing M phi caused tumor regression after 10 days, and prolonged life until 43 +/- 4 days with tumor-bearing M phi and 39 +/- 3 days with normal M phi. Untreated normal or tumor-bearing M phi were unable to cause the effect (30 +/- 2 days), and lymphocytes could not be substituted for M phi (25 +/- 3 days). In x-irradiated recipients, no effect of LK-activated M phi could be observed (control = 19 +/- 2 days; LK-activated tumor-bearing M phi = 21 +/- 3 days). In addition, administration of an admixture of LK-treated M phi and x-rayed tumor before challenge with viable P815 enabled the recipient to inhibit tumor growth and caused tumor necrosis with inflammatory cell infiltration of the tumor. These observations suggest that, in part, LK-activated M phi may interact in vivo with host-derived cellular components and enhance the immune reactivity of the host against the tumor.     

In vitro proliferation and in vivo malignancy of cell lines simultaneously derived from a chemically-induced heterogeneous rat mammary tumor

Summary Identification of clones in primary tumors responsible for proliferation, invasion, and metastasis was carried out. Four different aneuploid established cell lines derived from a ductal infiltrating mammary rat tumor induced by 7,12-dimethylbenz[a]anthracene were studied for proliferative and growth features in vitro and for tumorigenic and metastatic potential in vivo in nude mice. Clones, named RM1, RM2, RM3, and RM4, were characterized by different proliferative activity. Clone RM1 showed the highest proliferative activity by both tritiated thymidine incorporation and S-phase flow cytometry, followed by clone RM4. Conversely, clones RM2 and RM3 showed a lower proliferation rate. Growth-promoting activity, tested on 3T3 Swiss cells, was high in all clones, although RM1 showed significantly lower growth factors—releasing activity. Nude mice tumorigenesis demonstrated a strong tumor induction of line RM1 (100% of the mice after 47±7 d) and a slightly lower tumor induction of line RM4 (70% of the mice after 69±9 d). Line RM3 showed tumor induction in 40% of the mice after 186±16 d. Lines RM2 showed no tumor induction. Metastasis occurred in mice treated with line RM1 only. Therefore, tumorigenesis and metastasis correlate with proliferation but not with the release of growth factors. In conclusion, flow cytometry monitoring of clones from heterogeneous primary tumors proved to be a suitable model for the study of in vivo malignancy and in vitro proliferation.     

Evaluation of cytotoxicity and immune modulatory activities of soyasaponin Ab: An in vitro and in vivo study

To improve the immune efficacy of protein subunit vaccines, novel adjuvants are needed to elicit a suitable protective immune response and to promote long term immunologic memory. In this work, soyasaponin Ab, a major constituent among group A soyasaponins in soybeans was purified and prepared from soy hypocotyls. The immunomodulatory effects of soyasaponin Ab both in vitro and in vivo were investigated, and its pro-immunomodulatory molecular mechanism was also studied. For in vitro assays, with mouse macrophage cell line RAW264.7 as the studying model, both cytotoxicity and immune stimulatory activity were investigated to evaluate the potential of soyasaponin Ab as the vaccine adjuvant. The results indicated that soyasaponin Ab could be significantly safer than Quillaja saponins (QS). Soyasaponin Ab showed no toxicities over the tested concentration ranges compared to QS. Soyasaponin Ab was proved able to promote releases of inflammatory cytokines like TNFα and IL-1β in a dose-dependent manner. Furthermore, NF-κB signalling was also activated by soyasaponin Ab effectively. In addition, with TLR4 gene expression of RAW264.7 cell inhibited by RNA interference, immune stimulatory effects by soyasaponin Ab dropped down significantly. On the other hand, the in vivo experiment results showed that anti-ovalbumin (OVA) IgG, IgG1, IgG2a, IgG2b were significantly enhanced by the soyasaponin Ab and QS groups (p < 0.05 or p < 0.01). The results suggested that compared to QS, soyasaponin Ab may represent a viable candidate for effective vaccine adjuvant. TLR4 receptor dependent pathway may be involved in immune stimulatory effects of soyasaponin Ab.     

In vivo bioluminescence imaging and histopathopathologic analysis reveal distinct roles for resident and recruited immune effector cells in defense against invasive aspergillosis

Background  

Invasive aspergillosis (IA) is a major cause of infectious morbidity and mortality in immune compromised patients. Studies on the pathogenesis of IA have been limited by the difficulty to monitor disease progression in real-time. For real-time monitoring of the infection, we recently engineered a bioluminescent A. fumigatus strain.     

Effects of a murine mammary tumor on in vivo and in vitro hemopoiesis

The effects of an autologous transplanted mammary tumor (RIII-T3) on hemopoiesis in RIII mice are described. Tumor-bearing animals died 30 to 40 days after inoculation and displayed splenomegaly, extreme neutrophilia, and moderately increased monocyte levels in the spleen, peripheral blood, and bone marrow. The precursors of neutrophils and monocytes, granulocyte/macrophage colony-forming cells (GM-CFC) were elevated in the spleen, bone marrow, and peripheral blood. RIII-T3-conditioned medium stimulated bone marrow GM-CFC and caused the myelomonocytic cell line, WEHI-3B, to differentiate in vitro. The conditioned medium did not stimulate erythroid, megakaryocyte, or eosinophil colony formation. When conditioned medium was fractionated, two peaks of activity corresponding to GM-CSF and G-CSF were observed, suggesting that the extreme neutrophilia observed in tumor-bearing animals may result from chronic exposure of the hemopoietic system to these hemopoietic hormones.     

Honokiol,a small molecular weight natural product,inhibits angiogenesis in vitro and tumor growth in vivo

Natural products comprise a major source of small molecular weight angiogenesis inhibitors. We have used the transformed endothelial cell line SVR as an effective screen of natural product extracts to isolate anti-angiogenesis and anti-tumor compounds. Aqueous extracts of Magnolia grandiflora exhibit potent activity in our SVR proliferation assays. We found that the small molecular weight compound honokiol is the active principle of magnolia extract. Honokiol exhibited potent anti-proliferative activity against SVR cells in vitro. In addition, honokiol demonstrated preferential inhibition of primary human endothelial cells compared with fibroblasts and this inhibition was antagonized by antibodies against TNF alpha-related apoptosis-inducing ligand. In vivo, honokiol was highly effective against angiosarcoma in nude mice. Our preclinical data suggests that honokiol is a systemically available and non-toxic inhibitor of angiogenesis and should be further evaluated as a potential chemotherapeutic agent.     

Evaluation of in vitro antagonism and of in vivo immune modulation and protection against pathogenic experimental challenge of two probiotic strains of Bifidobacterium animalis var. lactis

The aim of the present study was to compare the effect of intragastric administration with two strains of Bifidobacterium animalis subsp. lactis (Bifido A and Bifido B), in gnotobiotic and conventional mice, challenged with Salmonella Typhimurium. In vitro antagonism test showed that the two strains were able to produce antagonistic substances against various pathogenic microorganisms. In an ex vivo antagonism test the production of antagonistic substances was observed only against three out ten pathogens tested. Both Bifidobacterium strains were able to colonize and to maintain high population levels in the digestive tract of gnotobiotic mice. In addition, the two strains had low and limited translocation ability and did not cause any histological lesion in any of the organs analyzed. Both strains were able to reduce the fecal number of Salmonella in gnotobiotic mice challenged with the pathogen, but only Bifido B was able to confer a protection as demonstrated by a lower mortality. Higher levels of sIgA and IL-10 were observed only in Bifido B mono-associated mice when compared to germ free group. We could conclude that, among the parameters analyzed, the strain Bifido B exhibited the more desirable characteristics to be used as a probiotic.     

Lymphocytes generated by in vivo priming and in vitro sensitization demonstrate therapeutic efficacy against a murine tumor that lacks apparent immunogenicity

The adoptive transfer of sensitized lymphocytes is an effective means to mediate the regression of established tumors. However, successful therapy can only be demonstrated in animal models where tumors are intrinsically immunogenic, capable of eliciting systemic immunity. To explore the potential of this therapeutic approach to tumors of less immunogenicity, we have selected and used a murine tumor, MCA 102, for the current study because all attempts to immunize syngeneic mice failed. We report here that inoculation of mice with a mixture of tumor cells and a bacterial adjuvant, Corynebacterium parvum led to the production of sensitized, but not fully functional, lymphocytes in the draining lymph nodes (LN). These cells, termed pre-effector cells, could nevertheless further differentiate to acquire full immunologic function by an established in vitro sensitization culture method. In adoptive immunotherapy experiments, transfer of as few as 1.5 X 10(7) in vitro sensitized cells not only reduced established pulmonary MCA 102 metastases but also prolonged survival and cured tumors in a majority of the treated animals. In order to elicit pre-effector cells in vivo, inoculation with both tumor cells and C. parvum was essential. Although a broad range of numbers of MCA 102 tumor cells appeared to be effective, generation of pre-effector cells was dependent on the dose of C. parvum. We have found that a C. parvum dose of 25 micrograms was optimal, whereas higher doses of the adjuvant had suppressive effects. Analysis of the kinetics of their appearance revealed that the generation of pre-effector cells was transient. They were detectable 7 days after in vivo priming followed by a rapid decline. Furthermore, pre-effector cells were detected only in the regional draining LN. No reactivity was demonstrable in the spleen, mesenteric LN, PBL, or bone marrow. Taken together, these results expand the scope of immunotherapy by demonstrating the feasibility of manipulating a limited and obscure immune response to the MCA 102 tumor for therapeutic efficacy.     

In vivo and in vitro macrophage activation induced by IFN gamma spontaneously released by spleen cells from tumor bearing mice.

Peritoneal macrophages obtained from Lewis Lung carcinoma (3LL) tumor bearing mice release high amounts of soluble factors such as C3,H2O2 and lysosomal enzymes but fail to exert cytotoxic activity on tumor cells. In the present work we show that they acquire this property and become fully activated after in vitro incubation with supernatants derived from cultures of splenocytes from tumor bearing syngeneic mice. The presence of IFN gamma in the above supernatants was detected by immunoblotting analysis and by bioassay. The role played by IFN gamma in macrophage activation was investigated.     

Suppression of the in vitro secondary response to syngeneic tumor and of in vivo tumor therapy with immune cells by culture-induced suppressor cells.

Mice with advanced disseminated syngeneic tumor can be successfully treated with a combination of chemotherapy and adoptively transferred syngeneic immune cells. We have previously demonstrated that in vivo primed cells secondarily sensitized in vitro became more effective in tumor therapy, whereas primed cells cultured for 5 days without tumor stimulation became less effective than an equal number of uncultured fresh primed cells. Therefore, we examined stimulated and unstimulated cultures of tumor-primed cells for the presence of culture-induced suppressor cells, and determined whether in vivo tumor therapy with immune cells could be inhibited by concurrent inoculation of immune effector cells and cultured normal spleen cells, which contain culture-induced suppressor cells but are devoid of additional effector cells. The in vitro primary allogeneic response was suppressed by cultured normal spleen cells, or tumor-primed spleen cells previously cultured for 5 days with or without tumor stimulation. In vitro secondary sensitization to syngeneic tumor was suppressed by normal or tumor-primed cells that had previously been cultured for 5 days without stimulation. The majority of this suppression was mediated by T cells in the cultured populations. The efficacy of fresh tumor-primed cells, as well as primed cells secondarily sensitized in vitro, in adoptive chemoimmunotherapy of advanced tumor was diminished by concurrent inoculation of cultured normal cells. The cells mediating suppression of in vivo therapy required previous in vitro culture for induction, and were radiation sensitive.     

Transfer in vivo of cytotoxic immune lymphocytes obtained in vitro in primary culture against a murine lymphoma antigenically altered by DTIC]

Specific cytotoxic T cells were obtained by coculturing "in vitro" normal spleen cells with inactivated histocompatible DTIC-altered lymphoma cells. The "in vivo" antitumor activity of such sensitized lymphocytes was evaluated by injecting a mixture of lymphocytes + tumor into the brains of lethally irradiated syngenic mice. The results indicated that such lymphocytes demonstrate antitumor activity against the same tumor but not against unrelated tumors.