The antitumour activity of 5,6-dimethylxanthenone-4-acetic acid (DMXAA) in TNF receptor-1 knockout mice

5,6-dimethylxanthenone-4-acetic acid, a novel antivascular anticancer drug, has completed Phase I clinical trial. Its actions in mice include tumour necrosis factor induction, serotonin release, tumour blood flow inhibition, and the induction of tumour haemorrhagic necrosis and regression. We have used mice with a targeted disruption of the tumour necrosis factor receptor-1 gene as recipients for the colon 38 carcinoma to determine the role of tumour necrosis factor signalling in the action of 5,6-dimethylxanthenone-4-acetic acid. The pharmacokinetics of 5,6-dimethylxanthenone-4-acetic acid, as well as the degree of induced plasma and tissue tumour necrosis factor, were similar in tumour necrosis factor receptor-1−/− and wild-type mice. However, the maximum tolerated dose of 5,6-dimethylxanthenone-4-acetic acid was considerably higher in tumour necrosis factor receptor-1−/− mice (>100 mg kg−1) than in wild-type mice (27.5 mg kg−1). The antitumour activity of 5,6-dimethylxanthenone-4-acetic acid (25 mg kg−1) was strongly attenuated in tumour necrosis factor receptor-1−/− mice. However, the reduced toxicity in tumour necrosis factor receptor-1−/− mice allowed the demonstration that at a higher dose (50 mg kg−1), 5,6-dimethylxanthenone-4-acetic acid was curative and comparable in effect to that of a lower dose (25 mg kg−1) in wild-type mice. The 5,6-dimethylxanthenone-4-acetic acid -induced rise in plasma 5-hydroxyindoleacetic acid, used to reflect serotonin production in a vascular response, was larger in colon 38 tumour bearing than in non-tumour bearing tumour necrosis factor receptor-1−/− mice, but in each case the response was smaller than the corresponding response in wild-type mice. The results suggest an important role for tumour necrosis factor in mediating both the host toxicity and antitumour activity of 5,6-dimethylxanthenone-4-acetic acid, but also suggest that tumour necrosis factor can be replaced by other vasoactive factors in its antitumour action, an observation of relevance to current clinical studies

Microenvironmental regulation of metastasis

Metastasis is a multistage process that requires cancer cells to escape from the primary tumour, survive in the circulation, seed at distant sites and grow. Each of these processes involves rate-limiting steps that are influenced by non-malignant cells of the tumour microenvironment. Many of these cells are derived from the bone marrow, particularly the myeloid lineage, and are recruited by cancer cells to enhance their survival, growth, invasion and dissemination. This Review describes experimental data demonstrating the role of the microenvironment in metastasis, identifies areas for future research and suggests possible new therapeutic avenues

Muramyldipeptide Modulates CXCL‐8 Release of BEAS‐2B Cells via NOD2

Chronic inflammation and acute exacerbations are pathophysiological features of chronic obstructive pulmonary disease (COPD). An impaired immune response to bacterial pathogens can contribute to both of them. Nucleotide oligomerization domain 2 (NOD2) is an intracellular receptor of innate immunity for muramyldipeptide (MDP). Mutations of the NOD2 gene followed by decreased recognition of MDP are associated with chronic intestinal inflammation and pulmonary complications of patients with allogenic stem cell transplant and sepsis. Our study provides evidence that NOD2, toll-like receptor 4 (TLR4) and the adapter protein receptor-interacting protein 2 (RIP2) are induced by tumor-necrosis factor-alpha (TNF-alpha,) and interferon-gamma (IFN-gamma) in the bronchial epithelial cell line BEAS-2B. We also demonstrate that lipopolysaccharide (LPS) can further increase NOD2 transcription in a TNF-alpha and IFN-gamma-induced activation state. In addition, we show that, while MDP fails to I enhance CXCL-8 release from otherwise unstimulated BEAS-213 cells a 12 11, prestimulation period with TNF-alpha and IFN-gamma primes the cells for an additional increase of CXCL-8 secretion via induction of NOD2 and RIP2. LPS itself significantly augments CXCL-8 production and co-administration of MDP further increases cytokine secretion. Finally, overexpression of an SNP 13 mutant decreased MDP-induced chemokine production in BEAS-213 cells compared with NOD2 wild type overexpression. Taken together, our work indicates that MDP and NOD2 play an important role for CXCL-8 release of BEAS-213 cells following LPS-challenge via synergistic interactions between MDP and LPS

NKG2D-dependent effector function of bronchial epithelium activated alloreactive T cells.

Allogeneic hematopoietic stem cell transplantation (SCT) has emerged as a curative therapeutic option. However, The role of graft-versus-host disease in lung injury after SCT has still to be determined.In the present study primary bronchial epithelial cells and the bronchial epithelial cell line BEAS-2B were used to investigate immune responses of allogeneic CD8(+) T- cells directed against respiratory epithelial cells.Following stimulation with irradiated bronchial epithelial cells, CD8(+) T-cells produced significant amounts of IFN-gamma, upregulated alloantigen activation markers and proliferated highly compared to T-cells stimulated with IL-2 alone. Furthermore, cytotoxicity assays demonstrated that bronchial epithelial cell specific and Granzyme B-mediated cytolytic activity was induced in CD8(+) T cells. Generation of NK-, NK-like T cells (NKT cells), cytokine-induced killer (CIK) or lymphokine activated killer (LAK) cells could be excluded by phenotyping, culture conditions and neglectable lytic activity following stimulation with IL-2 alone. Inhibition experiments showed that lysis of bronchial epithelial cells was not MHC I restricted but depended on natural killer group 2, member D (NKG2D) signaling, a stimulatory receptor initially shown to be expressed on NK cells.Our data imply that respiratory epithelium has antigen presenting function and directly alloactivates cytotoxic CD8(+) T cells which show nonclassical effector function

Upregulation of TNF Receptor Type 2 in Human and Experimental Renal Allograft Rejection

An important role of TNF interacting with TNFR2 has been shown in different models of ischemic, nephrotoxic and immune-mediated renal injury. To systematically evaluate the expression of TNFR2 in renal allograft rejection, we investigated human renal allograft biopsies and, in addition, established an experimental transplantation model in rats to verify the human data under standardized conditions. The expression of TNFR2 was analyzed in 96 human renal allograft biopsies with different disease entities. In a 6-day and a 28-day experimental protocol, TNFR2 was examined in kidney specimens and in the urine of control, uni-nephrectomized and transplanted rats +/- cyclosporine treatment (n = 114). In human biopsies and in rat allografts on day 6 with acute allograft rejection, significantly elevated expression of TNFR2 was observed in tubular epithelial cells, podocytes, B cells and monocytes/macrophages. The expression level was associated with renal function. The TNFR2 expression level at day 28 was significantly lower compared to day 6. TNFR2 is markedly upregulated both in human and experimental acute renal allograft rejection. Our data are robust and consistent between different species, suggesting a role for TNFR2 in the early course of rejection

Effects of selective and unselective endothelin‐receptor antagonists on prostacyclin synthase gene expression in experimental pulmonary hypertension

Objective. Compared to the unselective endothelin (ET) receptor antagonist (Bosentan), superior effects of selective ET-A-receptor blockage (Ambrisentan) for the treatment of pulmonary hypertension (PH) are expected due to ET-B-receptor mediated beneficial effects. Our hypothesis was that treatment with Ambrisentan leads to an increase in prostacyclin synthase I (PGIS) expression compared to Bosentan. Material and methods. To test this hypothesis, rats were treated with either monocrotaline (MCT) only, MCT+Ambrisentan or MCT+Bosentan. After 4 weeks, right ventricular systolic pressure (RVSP), pulmonary vascular remodelling and right ventricular hypertrophy(RV/(LV+S)) were measured. Results. In MCT only treated animals, significantly greater expression of PGIS mRNA was found in the lungs compared to control animals, and this was confirmed by immunohistochemical analysis indicating increased staining of PGIS in the very small pulmonary arteries (17% greater expression of PGIS mRNA in MCT versus control, p=0.002; Remmele score (RS): 51 versus 102, p=0.009). Treatment with Bosentan resulted in a significantly lower expression of PGIS mRNA compared to Ambrisentan and MCT only (7% versus 18%, p=0.003 and 7% versus 17 %, p=0.004). This observation was also confirmed by immunohistochemical analysis (RS very small arteries: 45 versus 81, p=0.003; RS small arteries: 45 versus 108, p=0.014). No difference was observed in RVSP, RV/(LV+S) or pulmonary vascular remodelling between the two treatment groups (RVSP: 28 versus 39 mmHg, p=0.189; RV/( LV+S) 0.46 versus 0.48, p=0.818; medial area: 78.3% versus 75.2%, p=0.823). Conclusions. Treatment with Bosentan leads to lower PGIS expression in pulmonary arteries compared to Ambrisentan, although the greater PGIS expression by Ambrisentan treatment had no benefical effect on pulmonary haemodynamics