TLR1/TLR2 agonist induces tumor regression by reciprocal modulation of effector and regulatory T cells

Using TLR agonists in cancer treatment can have either beneficial or detrimental effects. Therefore, it is important to determine their effect on the tumor growth and understand the underlying mechanisms in animal tumor models. In this study, we report a general immunotherapeutic activity of a synthetic bacterial lipoprotein (BLP), a TLR1/TLR2 agonist, on established lung carcinoma, leukemia, and melanoma in mice. Systemic treatment of 3LL tumor-bearing mice with BLP, but not LPS, led to a dose-dependent tumor regression and a long-lasting protective response against tumor rechallenge. The BLP-mediated tumor remission was neither mediated by a direct tumoricidal activity nor by innate immune cells, because it lacked therapeutic effect in immunodeficient SCID mice. Instead, BLP treatment reduced the suppressive function of Foxp3(+) regulatory T cells (Tregs) and enhanced the cytotoxicity of tumor-specific CTL in vitro and in vivo. Furthermore, adoptive cotransfer of BLP-pretreated but not untreated CTL and Tregs from wild-type but not from TLR2(-/-) mice was sufficient to restore antitumor immunity in SCID mice by reciprocally modulating Treg and CTL function. These results demonstrate that the TLR1/TLR2 agonist BLP may have a general tumor therapeutic property involving reciprocal downregulation of Treg and upregulation of CTL function. This property may play an important role in the development of novel antitumor strategies.

Selective impairment of CD4+CD25+Foxp3+ regulatory T cells by paclitaxel is explained by Bcl-2/Bax mediated apoptosis

Paclitaxel has become one of the most effective and widely used chemotherapeutic agents over the past decades. Although it has shown promise to selectively deplete regulatory T (Treg) cells in our previous study, the underlying molecular mechanism remains to be further elucidated. The present study focused on the effect of paclitaxel on Treg cells in 3LL Lewis tumor model and explored the possible molecular pathways involved in this process. We found that paclitaxel significantly decreased the percentage of Treg cells in CD4(+) cells and impaired their suppressive functions, but effector T (Teff) cells remained unaffected. Compared with Teff cells, Treg cells exhibited a high sensitivity to paclitaxel-mediated apoptosis in vitro. Interestingly, though paclitaxel has been characterized as a mitotic inhibitor, tubulin was not involved in the selective function of paclitaxel. Treg cells exposed to paclitaxel displayed downregulation of Bcl-2 and upregulation of Bax. Blocking the Bcl-2 pathway eliminated the difference between Treg and Teff cells responding to paclitaxel. These results suggest that Bcl-2 rather than tubulin contributes to the distinctive effect of paclitaxel on Treg cells. Therefore, we here identify a molecular pathway through which paclitaxel selectively ablates Treg cells.

Integrating individual functional moieties of CXCL10 and CXCL11 into a novel chimeric chemokine leads to synergistic antitumor effects: a strategy for chemokine-based multi-target-directed cancer therapy

The complexity of tumor biology necessitates a multimodality approach that targets different aspects of tumor environment in order to generate the greatest benefit. IFN-inducible T cell alpha chemoattractant (ITAC)/CXCL11 and IFN-inducible protein 10 (IP10)/CXCL10 could exert antitumor effects with functional specificity and thus emerge as attractive candidates for combinatorial strategy. Disappointedly, a synergistic antitumor effect could not be observed when CXCL10 and CXCL11 were pooled together. In this regard, we seek to improve antitumor efficacy by integrating their individual functional moieties into a chemokine chimeric molecule, designated ITIP, which was engineered by substituting the N-terminal and N-loop region of CXCL10 with those of CXCL11. The functional properties of ITIP were determined by chemotaxis and angiogenesis assays. The antitumor efficacy was tested in murine CT26 colon carcinoma, 4T1 mammary carcinoma and 3LL lung carcinoma. Here we showed that ITIP not only exhibited respective functional superiority but strikingly promoted regression of established tumors and remarkably prolonged survival of mice compared with its parent chemokines, either alone or in combination. The chemokine chimera induced an augmented anti-tumor immunity and a marked decrease in tumor vasculature. Antibody neutralization studies indicated that CXCL10 and CXCL11 moieties of ITIP were responsible for anti-angiogenesis and chemotaxis in antitumor response, respectively. These results indicated that integrating individual functional moieties of CXCL10 and CXCL11 into a chimeric chemokine could lead to a synergistic antitumor effect. Thus, this integration strategy holds promise for chemokine-based multiple targeted therapy of cancer.

Renal cell carcinoma may evade the immune system by converting CD4+Foxp3- T cells into CD4+CD25+Foxp3+ regulatory T cells: Role of tumor COX-2-derived PGE2

Increased CD4+CD25+Foxp3+ regulatory T cells (Tregs) predict poor prognosis in renal cell carcinoma (RCC). The aim of this study was to investigate the underlying causes of the aberrant accumulation of Tregs in RCC. pcDNA3.1-hCOX-2 and control pcDNA3.1 were transfected into the RCC cell line OS-RC-2. Under stimulation of anti-CD3/CD28 antibody and APC cells, isolated CD4+Foxp3- T cells were co-cultured with transfected OS-RC-2 culture medium supernatants and different control supernatants, respectively, and 96 h later, the proportion of Tregs in each group was detected using FACS. The suppressive ability of naturally isolated Tregs and transformed Tregs was also analyzed using [3H]-thymidine methods. The results showed that overexpression of COX-2 in OS-RC-2 cells led to higher expression of prostaglandin E2 (PGE2) in the culture medium supernatants. In addition, there was an apparent incremental increase in the percentage of Tregs in the CD4+Foxp3- T cells cultured with the COX-2-overexpressing OS-RC-2 culture medium supernatants. Furthermore, transformed Tregs had the same suppressive ability as naturally isolated Tregs. In summary, transfected RCC cell line culture medium supernatants were capable of converting CD4+Foxp3- T cells to Tregs by producing high levels of PGE2, while COX-2 inhibitors reduced the proportion of transformed Tregs in a dose-dependent manner. Thus, COX-2 inhibitors may induce a local anti-tumor effect and, in turn, may contribute to the eradication of RCC by decreasing transformed Tregs.

Generalisation of a procedure for computing transcription factor profiles

The limited amount of quantitative experimental data generated from life-science experiments poses a major challenge in systems biology. The reason for this is that many systems approaches, such as parameter estimation, simulation and sensitivity analysis make use of models or analyse quantitative data. However, these techniques are only of limited use if only qualitative or semi-quantitative information is available about a system. Therefore procedures that generate quantitative data from experiments in the life sciences can greatly expand the use of systems approaches to biological problems. This study addresses this issue as it introduces a procedure that computes quantitative transcription factor profiles from fluorescent microscopy data collected from green fluorescent protein (GFP) reporter cells. This technique forms a generalisation of a method that has recently been introduced for monitoring NF-B profiles. The contribution made in this work is that the assumption that the transcription factor profile exhibits damped oscillations is relaxed, as transcription factors, other than the previously investigated NF-B, may exhibit different profiles. This is achieved by investigating a variety of potential profiles and solving the inverse problem for the model describing transcription, translation and activation of GFP for each one. The transcription factor profile that results in the best fit among the potential candidates, for the measured fluorescent intensity data, is then chosen as the most likely concentration profile. The technique is illustrated in two detailed case studies, where one case study involves simulation data whereas the other one uses experimentally derived fluorescent intensity data.

Absence of IL-23p19 in donor allogeneic cells reduces mortality from acute GVHD

The p19 dimer of interleukin 23 (IL-23) has been reported to have a major role in the pathogenesis of many experimental and clinical autoimmune diseases and may also have a prominent role in transplantation. We reasoned that deficiency of p19 in the allogeneic donor transplant might reduce the inflammation caused by acute GVHD (aGVHD). The major histocompatibility complex-2 (H2(d)) BALB/c mice were subjected to 8.5 Gy TBI, followed by transplantation with 10 x 10(6) BM and 2.5 x 10(6) spleen cells from H2(d) BALB/c, H2(b) C57Bl/6 (B6) or H2(b) p19-/- donors. In all, 75% of the p19-/- transplanted mice survived, compared with only 12.5% of the B6 transplanted mice. This superior survival is correlated with significantly less severe aGVHD, absence of p19 after transplantation, less upregulation of mRNA and lower serum levels of IL-17 as compared with the B6 transplants. TBI alone significantly upregulated transforming growth factor-beta (TGF-beta), IL-6 and p19 mRNA levels in host BALB/c mice, possibly providing the milieu to induce IL-17 in p19-/- donor cells. IL-22, another cytokine, the induction of which in T-helper 17 (Th17) cells is supported by p19, was upregulated in BALB/c hosts but not in transplanted B6 or p19 donor cells, and may not have had a major role in modifying aGVHD.

Induction of allogeneic mixed chimerism by immature dendritic cells and bone marrow transplantation leads to prolonged tolerance to major histocompatibility complex disparate allografts

Mixed chimerism has been shown to lead to prolonged major histocompatibility complex (MHC) disparate allograft survival and immune-specific tolerance; however, traditional conditioning regimes often involve myeloablation, which may pose a significant safety risk. In this study we examined the use of donor C57BL/6 (H-2(b)) immature dendritic cells (imDCs) to tolerize the BALB/c (H-2(d)) recipient to bone marrow transplantation (BMT), allowing the induction of mixed chimerism without immunosuppression or myeloablation. We showed that successful mismatched bone marrow engraftment can be achieved using imDCs given up to 3 days prior to BMT and that mixed chimerism can be established and detected in excess of 100 days post-BMT without evidence of graft-versus-host disease. Furthermore, we showed that imDCs can suppress lymphocyte proliferation in response to mismatched MHC stimulation, leading to increased expression of interleukin (IL)-4 and IL-10 and decreased expression of IL-2 and interferon-gamma (IFN-gamma). The induction of stable chimeras through pre-conditioning of mice with donor imDCs followed by BMT led to tolerance, allowing the long-term survival (> 110 days) of mismatched cardiac allografts and the prolonged survival of mismatched skin allografts without the need for immunosuppression or myeloablation. Transplantation with third-party C3H allografts were rapidly rejected in this model, suggesting that immune-specific tolerance was achieved. The induction of immune-specific tolerance without the need for immunosuppression or myeloablation represents a significant advance in transplant immunology and may provide clinicians with a plausible alternative in combating organ rejection following transplantation.

Brushing effects on the growth and mechanical properties of Corispermum mongolicum vary with water regime

High water availability and mechanical stress can induce opposite responses in plants. In arid areas of Northern China the occurrence of high wind and high water availability tend to be negatively correlated. Since turgor pressure is a determinant of the mechanical stability of annuals, it is hypothesised that the effects of mechanical perturbation (MP) on annuals may depend on soil water availability. To test this proposal, we conducted an experiment in which a pioneering annual Corispermum mongolicum was subjected to two levels of MP and water supply, and then determined its growth and mechanical traits. Brushing had no effect on plant height and total biomass, but stimulated leaf and branch production. Water supply affected plant height, basal diameter, total biomass and stem rigidity, but not leaf and branch number, root/shoot ratio or flexibility. With high water availability, brushing stimulated the production of stiffer stems (thicker and with a higher Young's modulus) and more roots relative to shoot mass, but with low water availability MP induced the opposite response. This shows that both the degree and direction of plant responses to MP depend on the presence of other factors. We discuss how the interactive effects of MP and water availability on growth and mechanical properties may help C. mongolicum to establish in windy and arid environments.

Antifungal Activity in Transgenic Peanut (Arachis hypogaea L.) Conferred by a Nonheme Chloroperoxidase Gene

A nonheme chloroperoxidase gene (cpo-p) from Pseudomonas pyrrocinia, a growth inhibitor of mycotoxin-producing fungi, was introduced into peanut via particle bombardment. The expression of the cpo-p gene is predicted to increase pathogen defense in peanut. Embryogenic peanut tissues were bombarded with gold particles coated with plasmid pRT66 carrying the cpo-p and hygromycin phosphotransferase (hph) genes, under the control of a double CaMV 35S and a single CaMV 35S promoter, respectively. Selection for hygromycin-resistant somatic embryos was performed on a liquid medium containing 10–20 mg/L hygromycin 3–4 days after bombardment. The integration and expression of the cpo-p gene was confirmed by Southern, Northern and Western blot analyses. In vitro bioassay using crude protein extracts from transgenic T0, T1, and T4 plants showed inhibition of Aspergillus flavus hyphal growth, which could translate to a reduction in aflatoxin contamination of peanut seed.

Th17 and natural Treg cell population dynamics in systemic lupus erythematosus

OBJECTIVE

To investigate the relative abundance and activities of Th17 cells and natural Treg cells in systemic lupus erythematosus (SLE).

METHODS

Blood samples were collected from 50 adult patients with SLE. Samples were processed to detect Th17 cells and natural Treg cells by flow cytometry, and related gene expression was assessed by real-time reverse transcription-polymerase chain reaction. Skin biopsy specimens were collected for histologic assessment. The function of Th17 cells in relation to human umbilical vein endothelial cells (HUVECs) was studied in vitro. Th17 cells were also examined in lupus-prone MRL/Mp-lpr/lpr (MRL/lpr) mice.

RESULTS

We demonstrated the presence of Th17 cells among the peripheral blood mononuclear cells (PBMCs) and in the involved organs of patients with active SLE. Both the percentage of circulating Th17 cells and the ability to produce interleukin-17A (IL-17A) were increased in samples derived from patients with active SLE. The number of Th17 cells increased during SLE flare, especially in patients with vasculitis, and decreased following certain treatments. We observed that IL-17A from patients with SLE could induce adhesion molecule messenger RNA expression in HUVECs and adhesion of T cells to HUVECs. An increase in the percentage of Th17 cells was correlated with natural Treg cell depletion during disease flare. Finally, expansion of the Th17 cell population was detected in MRL/lpr mice.

CONCLUSION

SLE flare might be linked to the expansion of the Th17 cell population and the depletion of natural Treg cell subpopulations. Expansion of the Th17 cell population might be related to a distinct cytokine environment in active SLE. Th17 cells and microenvironmental IL-17A are involved in vascular inflammation in SLE. Antagonism of Th17 cells by IL-17A-blocking antibodies should be explored as a treatment of SLE.

Temporal and topographic alterations in expression of the alpha3 isoform of Na+, K(+)-ATPase in the rat freeze lesion model of microgyria and epileptogenesis

Na(+),K(+)-ATPase contributes to the asymmetrical distribution of sodium and potassium ions across the plasma membrane and to maintenance of the membrane potential in many types of cells. Alterations in this protein may play a significant role in many human neurological disorders, including epilepsy. We studied expression of the alpha3 isoform of Na(+),K(+)-ATPase in the freeze lesion (FL) microgyrus model of developmental epileptogenesis to test the hypothesis that it is downregulated following neonatal cortical injury. FL and sham-operated rat brains were examined at postnatal day (P)7, P10, P14, P21-28 and P50-60 after placement of a transcranial freeze lesion at P0 or P1. Immunohistochemistry and in situ hybridization were used to assess the expression of the alpha3 isoform of Na(+),K(+)-ATPase (termed alpha3, or alpha3 subunit below) in neuropil and the perisomatic areas of pyramidal cells and parvalbumin-containing interneurons. There was a significant decrease (P<0.05) in alpha3 subunit immunoreactivity (IR) in the neuropil of FL cortical layer V of the P14 and P21-28 groups that extended up to 360 mum from the border of the microgyrus, an area that typically exhibits evoked epileptiform activity. Alpha-3 was decreased in the perisomatic area of pyramidal but not parvalbumin-containing cells in P21-28 FL animals. A reduction in alpha3 mRNA was observed in the neuropil of FL cortical layer V up to 1610 mum from the microgyral edge. The developmental time course for expression of the alpha3 subunit between P7 and P60 was examined in naive rat cortices and results showed that there was a significant increase in alpha3 IR between P7 and P10. The significant decreases in Na(+),K(+)-ATPase in the paramicrogyral cortex may contribute to epileptogenesis.

Depletion of CD4(+)CD25(high) regulatory T cells from tumor infiltrating lymphocytes predominantly induces Th1 type immune response in vivo which inhibits tumor growth in adoptive immunotherapy

Adoptive cell transfer (ACT) immunotherapy administered with prior host immunosuppression significantly improved the anti-tumor efficacy in a murine model. However, bulk transfer of lymphocytes containing suppressor lymphocyte subsets, including regulatory T cells to mice bearing late-stage tumors impaired this anti-tumor effect. In this study, we investigated the enhanced anti-tumor efficacy by adoptive transfer of Treg-depleted autologous tumor infiltrating lymphocytes in advanced murine breast cancer. We found that, compared to bulk cell transfer, Treg-depleted cell transfer enhanced the activation and proliferation of both CD4(+) and CD8(+) T cells. Most importantly, the immune response deviated towards the Th1 response reflected by increased IFNgamma and reduced IL-4 secretion in both CD4(+) and CD8(+) T cells and an enhanced granzyme B release of CTL. Furthermore, the elicited Th1 response subsequently resulted in delayed tumor growth and prolonged mice survival as well as reduced lung metastasis in tumor-bearing nude mice. These results strongly indicated that Treg-depleted autologous cell transfer greatly enhanced Th1 type immune response, consequently leading to delayed tumor growth and reduced tumor burden. Therefore, ACT immunotherapy based on ex vivo selection of tumor-reactive lymphocytes resulted in enhanced anti-tumor immunity and provides important implications for further human studies.

Superoxide dismutase gene transfer reduces portal pressure in CCl4 cirrhotic rats with portal hypertension

BACKGROUND

Increased intrahepatic vascular tone in cirrhosis has been attributed to a decrease of hepatic nitric oxide (NO) secondary to disturbances in the post-translational regulation of the enzyme eNOS. NO scavenging by superoxide (O(2)(-)) further contributes to a reduction of NO bioavailability in cirrhotic livers.

AIM

To investigate whether removing increased O(2)(-) levels could be a new therapeutic strategy to increase intrahepatic NO, improve endothelial dysfunction and reduce portal pressure in cirrhotic rats with portal hypertension.

METHODS

Adenoviral vectors expressing extracellular superoxide dismutase (SOD) (AdECSOD) or beta-galactosidase (Adbetagal) were injected intravenously in control and CCl(4)-induced cirrhotic rats. After 3 days, liver O(2)(-) levels were determined by dihydroethidium staining, NO bioavailability by hepatic cGMP levels, nitrotyrosinated proteins by immunohistochemistry and western blot, and endothelial function by responses to acetylcholine in perfused rat livers. Mean arterial pressure (MAP) and portal pressure were evaluated in vivo.

RESULTS

Transfection of cirrhotic livers with AdECSOD produced a significant reduction in O(2)(-) levels, a significant increase in hepatic cGMP, and a decrease in liver nitrotyrosinated proteins which were associated with a significant improvement in the endothelium-dependent vasodilatation to acetylcholine. In addition, in cirrhotic livers AdECSOD transfection produced a significant reduction in portal pressure (17.3 (SD 2) mm Hg vs 15 (SD 1.6) mm Hg; p<0.05) without significant changes in MAP. In control rats, AdECSOD transfection prevents the increase in portal perfusion pressure promoted by an ROS-generating system.

CONCLUSIONS

In cirrhotic rats, reduction of O(2)(-) by AdECSOD increases NO bioavailability, improves intrahepatic endothelial function and reduces portal pressure. These findings suggest that scavenging of O(2)(-) might be a new therapeutic strategy in the management of portal hypertension.

Differential impairment of regulatory T cells rather than effector T cells by paclitaxel-based chemotherapy

Characterized as a mitotic inhibitor, paclitaxel has gained importance as a promising agent for the treatment of advanced non-small cell lung cancer (NSCLC). However, whether paclitaxel has immune modulatory effects remains unclear. In this study, we analyzed 55 peripheral blood samples from NSCLC patients who underwent paclitaxel-based chemotherapy. We found that among the lymphocyte subsets, paclitaxel selectively decreased the size of the regulatory T cell (Treg) population rather than other subsets including effector T cells (Teff). Apoptosis by upregulating the expression of the cell death receptor Fas (CD95) contributed to the reduced cell number of Treg. Importantly, the inhibitory function of Treg was significantly impaired, while the production of Th1 cytokines IFN-gamma and IL-2 and the expression of the activation marker CD44 among CD4(+) and CD8(+) T cells were augmented after paclitaxel treatment. These results strongly demonstrated that paclitaxel-based chemotherapy played important roles in modulating immune responses.

An anti-double-stranded DNA monoclonal antibody induced by tumor cell-derived DNA inhibits the growth of tumor in vitro and in vivo via triggering apoptosis

Serological presence of anti-double-stranded DNA (anti-dsDNA) antibodies is a common phenomenon in cancer patients. Some patients with relatively high levels of anti-dsDNA antibodies may have a better prognosis, indicating the potential antitumor roles of anti-dsDNA antibodies. To delineate the role and mechanisms of anti-dsDNA antibodies in delaying tumor development, here we prepared a panel of anti-dsDNA monoclonal antibodies (mAbs) and assessed their antitumor effects both in vitro and in vivo. After immunization of BALB/c mice with DNA from SP2/0 tumor cells, 12 anti-dsDNA mAbs were obtained. Among these mAbs, mAb 2G8 exhibited the strongest cytotoxicity to Wehi164 cells in vitro and significantly inhibited the growth of tumor in vivo. This mAb 2G8-mediated antitumor effect was mainly exerted by triggering apoptosis, as evidenced by Annexin V staining and DNA fragmentation. Further, the expression of antiapoptotic genes Bcl-2 and Bcl-xL was downregulated while that of pro-apoptotic gene Bax was upregulated, suggesting the involvement of mitochondrial apoptotic pathway. Taken together, dsDNA-specific mAb 2G8 revealed promising tumor-suppressive activity by inducing apoptosis, which provides a possible new strategy for the development of tumor intervening methods.

Resistance in Peanut Cultivars and Breeding Lines to Three Root-Knot Nematode Species

Three major species of root-knot nematode infect peanut: Meloidogyne arenaria race 1, M. hapla, and M. javanica race 3. Sources of resistance to all three nematodes are needed for developing novel peanut cultivars with broad resistance to Meloidogyne spp. Cultivars and breeding lines of peanut were evaluated for resistance to M. arenaria, M. hapla, and M. javanica in the greenhouse and in the laboratory. Twenty-six genotypes with some resistance to M. arenaria, M. javanica, or M. hapla were identified from 60 accessions based on average eggs per gram of root and gall index relative to a susceptible control. Among these, 14 genotypes were moderately to highly resistant to all three species, 5 genotypes were resistant to M. arenaria and M. javanica, 2 genotypes were resistant to M. javanica and M. hapla, 1 genotype was resistant M. arenaria alone, and 4 genotypes were resistant to M. hapla alone. Reproduction of M. arenaria on lines NR 0817, C724-19-11, and D108 was highly variable, indicating that these genotypes likely were heterogeneous for resistance. COAN, NemaTAM, C724-25-8, and the M. arenaria-resistant plants of C724-19-11 contained the dominant sequence-characterized amplified region marker (197/909) for nematode resistance. Results with the molecular markers indicate that the high resistance to M. arenaria in GP-NC WS 6 may be different from the resistance in COAN, NemaTAM, and C724-25-8. Resistance to M. arenaria was correlated with resistance to M. javanica in peanut, whereas resistance to M. hapla was not correlated with the resistance to either M. arenaria or M. javanica. The resistant selections should be valuable sources for pyramiding resistance genes to develop new cultivars with broad and durable resistance to Meloidogyne spp.