Listeria monocytogenes activated dendritic cell based vaccine for prevention of experimental tumor in mice

The use of dendritic cells [DCs] as a cellular adjuvant provides a promising approach in immunotherapy of cancer. It has been demonstrated that Listeria monocytogenes activated DCs pulsed ex vivo with tumor antigens trigger a systemic Th1-biased specific immune response and a single dose of this vaccine will cause a considerable anti tumor immunity. The present study was designed to evaluate the ability of multiple doses of tumor antigen-pulsed DCs, matured in the presence of Listeria monocytogenes components in induction of a potent anti-tumor response and the prevention of tumor formation in an experimental model. Bone-marrow derived DCs [BMDCs] were cultured in the presence of GM-CSF and IL-4. After 5 days, tumor lysates with/without Listeria monocytogenes lysate were added to the culture media for another 2 days. Mice received mature and tumor antigen pulsed dendritic cells subcutaneously in 3 groups. Tumor growth was monitored and two weeks after immunotherapy, cytotoxic activity of CD8+ T cells was evaluated in different groups. According to the findings, repeated doses of vaccine did not lead to a significant increase in the activity of cytotoxic T cells and decreased tumor growth of immunized animals. The current study suggests that increased doses of vaccine do not have sufficient efficiency for prevention of tumor induction. Generation of T regulatory responses upon repeated doses of such vaccines should be considered in future investigations

[Evaluation of different Listeria monocytogenes components on dendritic cells for eliciting TH1 response]

Dendritic cells [DCs] play a critical role in the beginning and in the course of immune responses. By observing. Considering the defect in these cells in patients with tumor malignancy. In recent years there has been considerable interests in correction and use of these cells. In our prvious studies we showed that lysate of Listeria monocytogenese can induce maturation of dendritic cells, and induce TH1 response and increase the survival of tumor in an experimental model. The main objective in the present study is to evaluate the effects of different constituents of Listeria monocytogenes on DCs and their efficiency to induce TH1 response. After preparation of different components of Listeria monocytogenese [lysate of Listeria monocytogenes, protein and nucleic acid components], mouse bone marrow cells were cultured for 5 days in the presence of IL-4 and GM-CSF and treated with different components of Listeria for another 2 days. DCs were evaluated for the expression of Co-stimulatory molecules, MHC Class II molecules and Cytokine secretion. The results showed that, all of the components are able to mature DCs efficiently and induce TH1 response. But dendritic cells matured with protein components shift the response to TH1 more efficiently. Our findings indicated that dendritic cell maturation protein components of Listeria monocytogenese shift the response to TH1 more efficiently and may have beneficial effects in cancer immunotherapy

Decreased T cell response to mitogen and increased anti-cytoplasmic antibody in drug-free schizophrenic patients

Apart from genetic and environmental factors, activation of autoreactive mechanisms has been proposed to play a role in the pathogenesis of schizophrenia. In recent years, considerable work has been carried out to understand the role and contribution of the immune system in this disease. To investigate the T cell response to phytohaemagglutinin [PHA] and determine the serum levels of anti-nuclear antibody [ANA], anti-cytoplasmic antibody [ACA], and circulating immune complexes [CIC] in schizophrenic patients. A total of 30 drug-free schizophrenic patients and 42 healthy controls were enrolled in this study. T cell proliferation in response to PHA was measured using Methyl Thiazol Tetrazolium test. ANA and ACA were measured by indirect immunofluorescence. CIC concentration was determined using poly ethylene glycol precipitation assay. Mean PHA response was 1.96 +/- 0.83 in patients and 3.72 +/- 1.39 in healthy controls [p < 0.001]. ANA and CIC concentrations were not significantly different between two groups. In addition, ACA was detected only in patients. Increased production of ACA together with lower T cell response to mitogens in our patients provides evidence for the involvement of autoimmune mechanisms in the pathogenesis of schizophrenia

Increased expression of trail and its receptors on peripheral T-cells in type 1 diabetic patients

Type-I diabetes is an autoimmune inflammatory disease in which pancreatic beta-cells are selectively destroyed by infiltrating cells. TNF-related apoptosis-inducing ligand [TRAIL] is a type-II membrane protein of the TNF superfamily which is expressed in different tissues, including pancreas and lymphocytes. In humans, TRAIL interacts with four membrane receptors. TRAIL-R1 and TRAIL-R2 have cytoplasmic death domains, and can activate both caspases and NF?B pathways. The other two receptors, TRAIL-R3 and TRAIL-R4, are decoy receptors not capable of activating caspase cascade but may activate NF-?B and block apoptosis. As human beta cells are sensitive to TRAIL induced apoptosis, signaling via these molecules is considered to be a probable way of beta cell destruction. These molecules also are important in suppression of autorective T cells and immunoregulation. To explore the importance of TRAIL and its receptors at pathogenesis of type-I diabetes, we compared expression of these molecules on T-cells of diabetic patients and healthy controls. In this study, expression of TRAIL and its receptors at protein and mRNA levels were studied in freshly isolated peripheral T cells of 55 type I diabetic patients and 50 healthy individuals by flowcytometry, western blot and RT-PCR. We found that expression of TRAIL and its receptors in peripheral T-cells at both protein and mRNA levels are significantly increased in patients [except for TRAIL-R2 mRNA which was slightly higher in controls] but increase in TRAIL, TRAILR3 [2.7% vs. >0.5%] and TRAIL-R4 [2.6% vs. >0.5%] is more considerable. sTRAIL in sera of patients was significantly lower than in controls [p=0.01]. Our results explain resistance of autoreactive T-cells to immunoregulatory mechanisms. Besides, increased expression of TRAIL in autoreactive T-cells may play an important role in betacell destruction. Lower level of sTRAIL in diabetic patients may be a reason for hyperactivation of autoreactive T-cells

Dendritic cell maturation with CpG for tumor immunotherapy

Bacterial DNA has immunostimulatory effects on different types of immune cells such as dendritic cells [DCs]. Application of DCs as a cellular adjuvant represents a promising approach in the immunotherapy of infectious disease and cancers. To investigate the effect of tumor antigen pulsed DCs in the presence of CpG-1826 in treatment of a murine model of cancer. WEHI-164 cells [Balb/c derived fibrosarcoma cell line] were injected subcutaneously in the right flank of mice. Bone marrow cells were cultured in the presence of GM-CSF and IL-4. After 5 days, tumor lysate, CpG-1826, and oligodeoxynucleosides, as control, were added to the culture media and incubated for 2 days. Cytokine production in DCs culture media was measured by ELISA. Then DCs were injected subcutaneously around the tumor site in the right flank of mice. Tumor growth rate was monitored in case and control groups. Two weeks after DCs immunotherapy, cytotoxic assay was conducted using various amounts of effector [splenic T cells] and target cells [WEHI-164 or CT26] for 6 h. Immunotherapy with DCs treated with CpG led to a significant increase in the activity of cytotoxic T cells and decreased tumor growth in immunized mice. In the control group which received DCs without CpG treatment, no change in cytotoxic activity and tumor growth rate was detected. The current study suggests that specific anti tumor immune responses can be induced by DCs matured with CpG and proposes CpG usage in DCs targeted clinical strategies

Increased natural killer cell activity in schizophrenic patients

Schizophrenia has been associated with altered immunity. Different studies regarding natural killer cell activity [NKA] in schizophrenic patients have shown inconsistent results. To evaluate NK cell activity in schizophrenic patients in comparison with healthy control individuals. 30 medication-free schizophrenic patients and 41 healthy sex, age and smoking status matched individuals were included in this study. NK cell activity of case and control subjects was measured by Methyl-Thiazol-Tetrazolium [MTT] test. Statistical analysis of the data was done using SPSS 11.5 software. NK activity of patients and normal subjects had a mean of 36.94 +/- 26.15 [Mean +/- SD] and 22.31 +/- 17.92, respectively. A significant increase in NK activity in schizophrenic patients compared to controls [P = 0.011]. Among patients, NK activity of smokers was significantly lower than that of non-smokers [P = 0.02]. Other demographic factors didn't show any influence on NK activity. The higher activity of NK cells in the schizophrenic patients as compared with the control population could explain the low incidence of cancer in these patients. Decreasing the effect of smoking on NK activity in the patients could be one of the responsible factors for the inconsistency in the results of different studies