Loss of B1 and marginal zone B cells during ovarian cancer

Recent advances in immunotherapy have not addressed the challenge presented by ovarian cancer. Although the peritoneum is an "accessible" locus for this disease there has been limited characterization of the immunobiology therein. We investigated the ID8-C57BL/6J ovarian cancer model and found marked depletion of B1 cells from the ascites of the peritoneal cavity. There was also selective loss of the B1 and marginal zone B cell subsets from the spleen. Immunity to antigens that activate these subsets validated their loss rather than relocation. A marked influx of myeloid-derived suppressor cells correlated with B cell subset depletion. These observations are discussed in the context of the housekeeping burden placed on innate B cells during ovarian cancer and to foster consideration of B cell biology in therapeutic strategies to address this challenge.

The somatically generated portion of T cell receptor CDR3α contributes to the MHC allele specificity of the T cell receptor

Mature T cells bearing αβ T cell receptors react with foreign antigens bound to alleles of major histocompatibility complex proteins (MHC) that they were exposed to during their development in the thymus, a phenomenon known as positive selection. The structural basis for positive selection has long been debated. Here, using mice expressing one of two different T cell receptor β chains and various MHC alleles, we show that positive selection-induced MHC bias of T cell receptors is affected both by the germline encoded elements of the T cell receptor α and β chain and, surprisingly, dramatically affected by the non germ line encoded portions of CDR3 of the T cell receptor α chain. Thus, in addition to determining specificity for antigen, the non germline encoded elements of T cell receptors may help the proteins cope with the extremely polymorphic nature of major histocompatibility complex products within the species.

CD28 ligation increases macrophage suppression of T-cell proliferation

When compared to spleen or lymph node cells, resident peritoneal cavity cells respond poorly to T-cell activation in vitro. The greater proportional representation of macrophages in this cell source has been shown to actively suppress the T-cell response. Peritoneal macrophages exhibit an immature phenotype (MHC class II(lo), B7(lo)) that reduces their efficacy as antigen-presenting cells. Furthermore, these cells readily express inducible nitric oxide synthase (iNOS), an enzyme that promotes T-cell tolerance by catabolism of the limiting amino acid arginine. Here, we investigate the ability of exogenous T-cell costimulation to recover the peritoneal T-cell response. We show that CD28 ligation failed to recover the peritoneal T-cell response and actually suppressed responses that had been recovered by inhibiting iNOS. As indicated by cytokine ELISpot and neutralizing monoclonal antibody (mAb) treatment, this 'cosuppression' response was due to CD28 ligation increasing the number of interferon (IFN)-γ-secreting cells. Our results illustrate that cellular composition and cytokine milieu influence T-cell costimulation biology.Cellular & Molecular Immunology advance online publication, 23 April 2012; doi:10.1038/cmi.2012.13.

Peritoneal T lymphocyte regulation by macrophages

The T cell composition of the peritoneal cavity (PerC) in naïve BALB/c, C57BL/6, DBA/2J, and B-1 B cell-defective BALB.xid mice was investigated. The BALB.xid PerC T cell pool had a high CD4:CD8 T cell ratio relative to the other strains whose ratios were similar to those found in their lymph node and spleen. All mice had significant representation of T cells with an activated (CD25(+), GITR(hi), CD44(hi), CD45RB(lo), CD62L(lo)) phenotype and low numbers of Foxp3(+) T(reg) cells in their PerC. Despite a phenotype indicative of activation, peritoneal T cell responses to CD3 ligation were very low for C57BL/6 and BALB.xid, but not BALB/c, mice. Enzyme inhibition and cytokine neutralization studies revealed active suppression of the T cell response mediated by the macrophages that represent a significant portion of PerC leucocytes. Driven by IFNγ to express iNOS, macrophages suppressed T cell activation in vitro by arginine catabolism. Although BALB/c T cells were also in a macrophage-dense environment their limited IFNγ production failed to trigger suppression. This difference between BALB/c and BALB.xid PerC T cells suggests a role for xid in shaping macrophage-mediated immune regulation.

Cytokine treatment of macrophage suppression of the Mls response (88.3)

Components of the immune system essential for curbing tumor progression are often found within the tumor. High macrophage to T cell ratios (Mö:T) are hallmarks of the tumor microenvironment. We have shown that such conditions suppress the immune response to the retroviral superantigen Mls by IFN ã -triggered production of the Arg- and Trp-consuming enzymes iNOS and IDO. In attempts to reverse suppression by treatment with pro-inflammatory cytokines, IL-6 improved the T cell response to Mls, IL-1 and TNFá had little effect, and the pro-hematopoietic cyokines IL-3 and GM-CSF increased suppression. GM-CSF treatment increased Mö expression of CD80, a significant ligand for the immunosuppressive B7H1 and CTLA-4 receptors. These results reveal avenues for reversal of the suppression of cell-mediated immunity characteristic of the high Mö:T cell ratios found in many tumors. Supported by NIH AREA R15-AI060356-01.

Cytokine treatment of macrophage suppression of T cell activation

High Mphi:T cell ratios suppress the immune response to the retroviral superantigen Mls by IFNgamma-triggered production of the arg- and trp-consuming enzymes iNOS and IDO. Attempts to reverse suppression by treatment with pro-inflammatory cytokines revealed that IL-6 improved the T cell response to Mls and the pro-hematopoietic cyokines IL-3 and GM-CSF increased suppression. GM-CSF treatment increased Mphi expression of CD80, a ligand for the immune suppressive B7H1 and CTLA-4 receptors. These results illustrate potential strategies for reversing the suppression of cell-mediated immunity characteristic of the high Mphi:T cell ratios found in many tumors.

Complementary suppression of T cell activation by peritoneal macrophages and CTLA-4-Ig

Peritoneal macrophages suppressed T lymphocyte activation by amino acid catabolism. CTLA-4-Ig complemented this form of suppression by blocking the costimulation of T cells. Inhibition of the amino acid catabolizing enzymes or blockade of the IFNgamma signaling essential for macrophage-mediated suppression did not impact CTLA-4-Ig efficacy. Except for phytohemagglutinin, T cell responses to superantigen, mitogen, and anti-CD3 were further reduced when CTLA-4-Ig was combined with peritoneal macrophages. The combination of these complimentary forms of immune regulation potently suppresses adaptive immunity.

Peritoneal macrophages suppress T-cell activation by amino acid catabolism

T-lymphocyte activation triggered by anti-CD3, endogenous or exogenous superantigen, and mitogens was suppressed in a cell-dose-dependent fashion by peritoneal cavity (PerC) leucocytes. Study of lymphocyte-deficient mice and the use of multiparameter fluorescence-activated cell sorter analyses revealed that macrophages were responsible for this form of immune regulation. Interferon-gamma was essential to trigger suppression, which, by enzyme inhibition studies, was shown to be the result of tryptophan and arginine catabolism. These results illustrate that macrophages, which are classically defined by their innate effector function as antigen-presenting cells, have the potential to temper adaptive immunity.

CF101, an agonist to the A3 adenosine receptor, enhances the chemotherapeutic effect of 5-fluorouracil in a colon carcinoma murine model

NF-kappaB and the upstream kinase PKB/Akt are highly expressed in chemoresistance tumor cells and may hamper the apoptotic pathway. CF101, a specific agonist to the A3 adenosine receptor (A3AR), inhibits the development of colon carcinoma growth in cell cultures and xenograft murine models. Because CF101 has been shown to downregulate PKB/Akt and NF-kappaB protein expression level, we presumed that its combination with chemotherapy will enhance the antitumor effect of the cytotoxic drug. In this study, we utilized 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and colony formation assays and a colon carcinoma xenograft model. It has been shown that a combined treatment of CF101 and 5-fluorouracil (5-FU) enhanced the cytotoxic effect of the latter on HCT-116 human colon carcinoma cell proliferation and tumor growth. Downregulation of PKB/Akt, NF-kappaB, and cyclin D1, and upregulation of caspase-3 protein expression level were observed in cells and tumor lesions on treatment with a combination of CF101 and 5-FU. Moreover, in mice treated with the combined therapy, myelotoxicity was prevented as was evidenced by normal white blood cell and neutrophil counts. These results show that CF101 potentiates the cytotoxic effect of 5-FU, thus preventing drug resistance. The myeloprotective effect of CF101 suggests its development as an add-on treatment to 5-FU.

Antiinflammatory effect of A3 adenosine receptor agonists in murine autoimmune arthritis models

OBJECTIVE

CF101, an A3 adenosine receptor (A3AR) agonist, is a small orally bioavailable molecule known to suppress in vitro the production of tumor necrosis factor-alpha (TNF-alpha). We evaluated its therapeutic potential and antiinflammatory effects in 3 murine models of adjuvant induced arthritis (AIA).

METHODS

The antiinflammatory effect of CF101 was examined in rat AIA, in mouse collagen induced arthritis, and in tropomyosin induced arthritis. The clinical effect of another A3AR agonist, Cl-IB-MECA, was examined in rat AIA. The effect of low dose (10 or 100 mg/kg/day) A3AR agonists administered orally once daily on arthritis severity was assessed clinically and histologically. The effect of CF101 on the protein expression level of TNF-alpha in the synovial tissue, draining lymph nodes, and spleen cells was determined by Western blot.

RESULTS

CF101 and Cl-IB-MECA markedly ameliorated the clinical and histological features of arthritis in the 3 models when administered orally at a low dose of 10 mg/kg body weight in the 3 autoimmune arthritis models. The lower dose of 10 mg/kg of either CF101 or Cl-IB-MECA had better antiinflammatory effect than the higher 100 mg/kg dose. Decreased expression of TNF-alpha was noted in protein extracts of synovia, draining lymph nodes, and spleen tissues.

CONCLUSION

The results provide evidence that A3AR agonists exert significant antirheumatic effects in different autoimmune arthritis models by suppression of TNF-alpha production. The beneficial activity of the drugs at the low dose demonstrates that the effect is A3AR mediated.

Inhibition of primary colon carcinoma growth and liver metastasis by the A3 adenosine receptor agonist CF101

Adenosine is a purine nucleoside that acts as a regulatory molecule by binding to specific G-protein-coupled A1, A(2A), A(2B), and A3 cell surface receptors. We have recently demonstrated that adenosine inhibits tumour cell growth and concomitantly stimulates bone marrow cell proliferation via activation of the A3 adenosine receptor (A3AR). In the present study, we show that a synthetic agonist to the A3AR, CF101, at the low nanomolar concentration range, inhibits HCT-116 human colon carcinoma cell growth. This effect was reversed by the selective A3AR antagonist MRS1523, demonstrating the specificity of the response. CF101 (given orally) was efficacious in inhibiting the development of primary tumours in xenograft and syngeneic models in which mice were inoculated subcutaneously with human HCT-116 or murine CT-26 colon carcinoma cells, respectively. Moreover, CF101 suppressed (50%, P<0.01) colon cancer liver metastases in syngeneic mice inoculated to the spleen with CT-26 cells. The mechanism of action entailed upregulation of interleukin-12 production in the CF101-treated groups and potentiation of NK cell activity. In the HCT-116 xenograft model in which a combined therapy of CF101 and 5-fluorouracyl (5-FU) was examined, an additive antitumour effect was demonstrated. Moreover, CF101 prevented the 5-FU-induced myelotoxicity, resulting in normal values of white blood cell and neutrophil counts. We conclude that the A3AR agonist CF101, a small orally bioavailable molecule, exerts systemic anticancer, antimetastatic, and myeloprotective effects in colon carcinoma-bearing mice, and may serve as an adjuvant treatment to enhance the chemotherapeutic index and prevent myelotoxicity.

Ependymomas: a clinical and pathologic study. Part II. Survival features

A survival analysis of cases of ependymoma was performed. Patients with ependymomas of the infratentorium were found to have shorter disease-free intervals and to live for a shorter time after treatment than those with tumors of the cauda equina. Children with infratentorial tumors did not have a recurrence if they survived 3 or more years after operation, whereas adults with infratentorial tumors could have a first recurrence even 5 or more years after surgery. Younger patients did not survive as long as older patients in the group of infratentorial ependymomas. In contrast, age did not influence survival in patients with cauda equina ependymomas. Patients with ependymomas of the infratentorium and the cauda equina having long histories had a better prognosis than those with short histories. Changes in mitotic index and tumor cell number could not be correlated with the length of survival. In the infratentorial group, patients with rosette-bearing tumors had a poor prognosis, whereas patients with subependymal areas in their tumor had a better prognosis. Total surgical removal with no further treatment appeared to be as effective as subtotal removal followed by radiotherapy for the cauda equina tumors.

Ependymomas: a clinical and pathologic study. Part I. Biologic features

A series of 102 Oxford ependymomas was analyzed by comparing certain clinical data with pathologic data obtained by a review of the histologic slides of the tumors. All the data analysis was performed by computer, thus permitting a rapid search of many parameters for relationships of statistical significance. Age and site were found to be associated with the duration of pre-operative symptoms, mitotic index, tumor cell number, and some specific histologic features.

Behavior of vanadate and vanadyl ion in canine blood

Radiolabeled vanadium as either vanadyl ion or vanadate ion was injected intravenously into adult beagle dogs, and blood samples were collected at various times up to 48 hr post injection. For each sample, the distribution of vanadium between the cells and the plasma was determined, and the plasma was analyzed by electrophoresis to identify specific vanadium-binding proteins. Initially, vanadyl ion left the bloodstream more rapidly than vanadate, but the rates equalized after about 5 hr. A significant fraction of the vanadium in blood was associated with the cellular component following injection of both forms of vanadium. About 77% of the plasma vanadium was eventually bound by the serum iron transport protein transferrin, regardless of the vanadium species initially injected. For both vanadyl and vanadate, about 30 hr were required to reach the maximum degree of transferrin binding.