IRF4-dependent dendritic cells regulate CD8+ T-cell differentiation and memory responses in influenza infection.

Acute respiratory disease caused by influenza viruses is imperfectly mitigated by annual vaccination to select strains. Development of vaccines that elicit lung-resident memory CD8+ T cells (TRM) would offer more universal protection to seasonal and emerging pandemic viruses. Understanding how lung-resident dendritic cells (DCs) regulate TRM differentiation would be an important step in this process. Here, we used CD11c-cre-Irf4f/f (KO) mice, which lack lung-resident IRF4-dependent CD11b+CD24hi DCs and show IRF4 deficiency in other lung cDC subsets, to determine if IRF4-expressing DCs regulate CD8+ memory precursor cells and TRM during influenza A virus (IAV) infection. KO mice showed defective CD8+ T-cell memory, stemming from a deficit of T regulatory cells and memory precursor cells with decreased Foxo1 expression. Transfer of wild-type CD11b+CD24hi DCs into KO mice restored CD8+ memory precursor cell numbers to wild-type levels. KO mice recovered from a primary infection harbored reduced numbers of CD8+ TRM and showed deficient expansion of IFNγ+CD8+ T cells and increased lung pathology upon challenge with heterosubtypic IAV. Thus, vaccination strategies that harness the function of IRF4-dependent DCs could promote the differentiation of CD8+ TRM during IAV infection.

A Major Population of Functional KLRG1- ILC2s in Female Lungs Contributes to a Sex Bias in ILC2 Numbers.

Humans show significant sex differences in the incidence and severity of respiratory diseases, including asthma and virus infection. Sex hormones contribute to the female sex bias in type 2 inflammation associated with respiratory diseases, consistent with recent reports that female lungs harbor greater numbers of GATA-3-dependent group 2 innate lymphoid cells (ILC2s). In this study, we determined whether sex hormone levels govern sex differences in the numbers, phenotype, and function of ILC2s in the murine lung and bone marrow (BM). Our data show that lungs of female mice harbor significantly greater ILC2 numbers in homeostasis, in part due to a major subset of ILC2s lacking killer-cell lectin like receptor G1 (KLRG1), a population largely absent in male lungs. The KLRG1- ILC2s were capable of type 2 cytokine production and increased with age after sexual maturity, suggesting that a unique functional subset exists in females. Experiments with gonadectomized mice or mice bearing either global or lymphocyte restricted estrogen receptor α (Esr1) deficiency showed that androgens rather than estrogens regulated numbers of the KLRG1- ILC2 subset and ILC2 functional capacity in the lung and BM, as well as levels of GATA-3 expression in BM ILC2s. Furthermore, the frequency of BM PLZF+ ILC precursors was higher in males and increased by excess androgens, suggesting that androgens act to inhibit the transition of ILC precursors to ILC2s. Taken together, these data show that a functional subset of KLRG1- ILC2s in females contributes to the sex bias in lung ILC2s that is observed after reproductive age.

The role of cell cycle progression for the apoptosis of cancer cells induced by palladium(II)-saccharinate complexes of terpyridine.

OBJECTIVES: Palladium complexes are potent and less toxic molecules in comparison to other metal based agents. Here, we characterized two palladium(II) saccharinate complexes with terpyridine for their cell cycle specificity. MATERIALS AND METHODS: Cells were arrested at G1, G1/S boundary or mitosis using mimosine, double-Thymidine block, aphidicolin, nocodazole or colcemid, and evaluated based on morphology and flow cytometry. Synchronized cells were treated with the Pd(II) complexes, and viability was measured via MTT assay. RESULTS: While treatment of arrested cells with the Pd(II) complexes resulted in no significant change in cell death in HCT-116 and MDA-MB-231 cells, HeLa cells were more sensitive in S/G1. The main form of cell death was found to be apoptosis. CONCLUSIONS: Pd(II) complexes appear to be cell-cycle non-specific, while cell line dependent differences may be observed. Cells die through apoptosis regardless of the cell cycle stage, which makes these complexes more promising as anti-cancer agents.

Human blood myeloid and plasmacytoid dendritic cells cross activate each other and synergize in inducing NK cell cytotoxicity.

Human blood dendritic cells (DCs) hold great potential for use in anticancer immunotherapies. CD1c+ myeloid DCs and plasmacytoid DCs (pDCs) have been successfully utilized in clinical vaccination trials against melanoma. We hypothesize that combining both DC subsets in a single vaccine can further improve vaccine efficacy. Here, we have determined the potential synergy between the two subsets in vitro on the level of maturation, cytokine expression, and effector cell induction. Toll-like receptor (TLR) stimulation of CD1c+ DCs induced cross-activation of immature pDCs and vice versa. When both subsets were stimulated together using TLR agonists, CD86 expression on pDCs was increased and higher levels of interferon (IFN)-α were produced by DC co-cultures. Although the two subsets did not display any synergistic effect on naive CD4+ and CD8+ T cell polarization, CD1c+ DCs and pDCs were able to complement each other's induction of other immune effector cells. The mere presence of pDCs in DC co-cultures promoted plasma cell differentiation from activated autologous B cells. Similarly, CD1c+ DCs, alone or in co-cultures, induced high levels of IFN-γ from allogeneic peripheral blood lymphocytes or activated autologous natural killer (NK) cells. Both CD1c+ DCs and pDCs could enhance NK cell cytotoxicity, and interestingly DC co-cultures further enhanced NK cell-mediated killing of an NK-resistant tumor cell line. These results indicate that co-application of human blood DC subsets could render DC-based anticancer vaccines more efficacious.

Hepatitis B virus e antigen (HBeAg) may have a negative effect on dendritic cell generation.

Hepatitis B virus (HBV) continues to be a serious worldwide health problem despite the use of protective HBV vaccines and therapeutic regimens against chronic HBV infection. Chronic HBV patients cannot induce sufficient immune responses against the virus. HBV and its antigens are believed to suppress immune responses during chronic infection. Hence, studying the role of HBV in immune suppression is very important for the development of alternative therapeutic strategies for HBV infections. In the present study, we investigated the effect of Hepatitis B virus e antigen (HBeAg) on the generation of bone marrow derived dendritic cells (BMDCs) and the stimulation of plasmacytoid DCs (pDCs). In the presence of HBeAg, the ratio of BMDCs was decreased, but the ratio of CD11b(+)Ly6G(+) immature myeloid cells was increased. The expression of 47 proteins was also changed during HBeAg treatment; however, CpG-induced MHC-II expression on pDCs was not affected. Our results indicate that HBeAg may have a negative effect on the generation of DCs from bone morrow precursors.

The value of frozen cartilage tissues without cryoprotection for genetic conservation.

Animal tissues frozen without cryoprotection are thought to be inappropriate for use as a donor for somatic cell nuclear transfer (SCNT) studies. Cells in tissues that have been frozen without a cryoprotectant are commonly thought to be dead or to have lost genomic integrity. However, in this study we show that the frozen auricular cartilage tissues of anatolian buffalo contain a considerable number of viable healthy cells. The cells in auricular cartilage tissues are resistant to cryo-injury at -80°C. Primary cell cultures were established from defrosted ear tissues which were frozen without cryoprotectant. The growth and functional characteristics of primary cell cultures are characterized according to cell growth curve, cell cycle analysis, karyotype and GAG synthesis. The results indicate that frozen cartilage tissues could be valuable materials for the conservation of species and SCNT technology.

Effects of fibronectin and type IV collagen on osteosarcoma cell apoptosis.

The aims of this study are the investigation of the effects of fibronectin and type IV collagen extracellular matrix proteins and the role of caspase-3 and -9 on cis-platin induced U2-OS apoptosis were studied. First the cytotoxic effects of cis-platin on cell system were investigated by colorimetric method and than morphological and ELISA analysis were used for determination of cell apoptosis when induced with cis-platin. In addition, after adhering the cells to fibronection or type IV collagen proteins, the apoptotic rate and the effects of caspase-3 and -9 were also investigated by ELISA in presence of specific inhibitors. U2-OS cells showed 20% cytotoxicity after treatment with 2.4 microM of cis-platin for 48 h. Morphological and the numerical data showed that cis-platin was able to induced apoptosis on cells as a dose-dependent manner. Caspase-3 and -9 inhibitors inhibited cis-platin-induced apoptosis in U2-OS cells, respectively. The binding of cells to 10 microg/mL of fibronectin but not type IV collagen enhanced the apoptosis about 2.5 fold that effects inhibited with caspase-3 inhibitor. The caspase-3 and -9 are involved in the apoptotic signals induced by cis-platin in U2-OS. The binding to fibronectin, but not type IV collagen enhanced the apoptotic response of U2-OS and fibronectin-dependent apoptosis was activated by caspase-3. These finding might be useful for patients to fight against osteosarcoma.

Biological assays on the effects of Acra3 peptide from Turkish scorpion Androctonus crassicauda venom on a mouse brain tumor cell line (BC3H1) and production of specific monoclonal antibodies.

Constitutes of the venom scorpion are a rich source of low molecular mass peptides which are toxic to various organisms, including man. Androctonus crassicauda is one of the scorpions from the Southeastern Anatolia of Turkey with public health importance. This work is focused on the investigation of biological effects of Acra3 peptide from Androctonus crassicauda. For this purpose, Acra3 isolated from crude venoms was tested for its cytotoxicity on BC3H1 mouse brain tumor cells using tetrazolium salt cleavage and lactate dehydrogenase activity assays. To determine whether the cytotoxic effects of Acra3 was related to the induction of apoptosis, the morphology of the cells and the nuclear fragmentation was examined by using Acridin Orange staining and DNA fragmentation assay, respectively. Caspase 3 and caspase 9 activities were measured spectrophotometrically and flow cytometric assay was performed using Annexin-V FITC and Propidium Iodide staining. Furthermore toxic peptide Acra3 was used as an antigen for immunological studies. Results showed that Acra3 exerted very strong cytotoxic effect on BC3H1 cells with an IC50 value of 5 µg/ml. Exposure of the cells to 0.1 and 0.5 µg/ml was resulted in very strong appearance of the apoptotic morphology in a dose dependent manner. On the other side, not any DNA fragmentation was observed after treatment of the cells. Caspase 3 and 9 activities were slightly decreased with Acra3. Results from flow cytometry and lactate dehydrogenase activity assays indicate that Acra3 exerts its effects by inducing a stronger necrosis than apoptosis in BC3H1 cells. To evaluate its immunogenicity, monoclonal antibody (MAb) specific for Acra3 antigen (5B9) was developed by hybridoma technology using spleen and lymph nodes of mice and immunoglobulin type of antibody was found to be IgM. We suggest that Acra3 may exert its effects by inducing both necrotic and apoptotic pathway in some way on mouse brain tumor cells. These findings will be useful for understanding the mechanism of cell death caused by venom in vitro. Anti-Acra3 monoclonal antibody can be further used as a bioactive tools for exploring the structure/function relationship and the pharmacological mechanism of scorpion peptide neurotoxins.

Monoclonal antibodies specific for hepatitis B e antigen and hepatitis B core antigen.

Despite effective vaccination programs in many countries, HBV infection is still a serious health problem throughout the world; more than 2 billion people have been infected with Hepatitis B virus (HBV). The serologic markers are crucial indicators in clinical diagnosis of HBV infection. The persistent presence of anti-HBc is associated with chronicity, and anti-HBe is an indicator for active viral replication. In the present study, two different hybridoma clones, 12E5 and 16F8, secreting anti-HBeAg and anti-HBc antibody were developed using hybridoma technology. BALB/c mice were immunized with HBe antigen (HBeAg), and monoclonal antibodies were generated from the spleen and lymph nodes of mice. Immunoglobulin types of antibodies were found to be IgG2a and IgG1, respectively. Monoclonal antibodies (MAbs) were produced in large scale, purified with affinity chromatography, and epitope analysis was performed. The results have shown that 12E5 and 16F8 monoclonal antibodies can be used for detection of HBcAg and HBeAg, indicating that they have the potential for use in clinical diagnosis.

Phage displayed HBV core antigen with immunogenic activity.

Hepatitis B is a major public health problem worldwide, which may lead to chronic liver diseases such as cirrhosis and hepatocellular carcinoma. The hepatitis B core antigen (HBcAg) is one of the major viral proteins, which forms the inner core of hepatitis B virus (HBV) particles. In this study, filamentous bacteriophage M13 was genetically modified to display the polypeptides of HBcAg in order to develop an alternative carrier system. HBcAg gene was inserted into the minor coat protein (pIII) gene of M13, and HBcAg was expressed on the phage surface as a whole protein. Antigenicity and immunogenicity of HBcAg were tested by immunizing BALB/c mice three times with HBcAg-displaying recombinant phages. After successful immunization, one of the mice with high antibody titer to HBcAg was selected for fusion, and four monoclonal antibodies specific for HBcAg were developed. This result showed that HBcAg-displaying recombinant bacteriophages are immunogenic and can potentially be used for the development of monoclonal antibodies.

Cryopreservation of spleen and lymph nodes as a source of mononuclear cells to be used for the development of monoclonal antibody producing hybridoma cells.

In the present study, spleen and lymph nodes of mice were cryopreserved as a whole tissue and after thawing, membrane integrity of mononuclear cells was determined by trypan blue exclusion and PI staining. T and B lymphocytes, macrophages and dendritic cells have been isolated from both cryopreserved tissue and analyzed by Flow cytometry. BALB/c mice were immunized with Hepatitis e antigen (HBeAg) and spleen and lymph nodes of mice were cryopreserved for 3 to 10 months. The cells obtained from both tissue were applied to hybridoma technology to understand if the cells keep their viability and functionality. The cells were isolated and fused with F0 mouse myeloma cells and several antibody producing hybrid cells were developed. Results have shown that cryopreserved spleen and lymph nodes of mice can be efficiently used in hybridoma technology for the successful generation of monoclonal antibody producing hybrid cells.