Differential effects of cyclo-oxygenase pathway metabolites on cytokine production by T lymphocytes

Biology of NSCLC: Interplay between Cancer Cells, Radiation and Tumor Immune Microenvironment

The overall prognosis and survival of non-small cell lung cancer (NSCLC) patients remain poor. The immune system plays an integral role in driving tumor control, tumor progression, and overall survival of NSCLC patients. While the tumor cells possess many ways to escape the immune system, conventional radiotherapy (RT) approaches, which are directly cytotoxic to tumors, can further add additional immune suppression to the tumor microenvironment by destroying many of the lymphocytes that circulate within the irradiated tumor environment. Thus, the current immunogenic balance, determined by the tumor- and radiation-inhibitory effects is significantly shifted towards immunosuppression, leading to poor clinical outcomes. However, newer emerging evidence suggests that tumor immunosuppression is an "elastic process" that can be manipulated and converted back into an immunostimulant environment that can actually improve patient outcome. In this review we will discuss the natural immunosuppressive effects of NSCLC cells and conventional RT approaches, and then shift the focus on immunomodulation through novel, emerging immuno- and RT approaches that promise to generate immunostimulatory effects to enhance tumor control and patient outcome. We further describe some of the mechanisms by which these newer approaches are thought to be working and set the stage for future trials and additional preclinical work.

XRCC5 cooperates with p300 to promote cyclooxygenase-2 expression and tumor growth in colon cancers

Cyclooxygenase (COX) is the rate-limiting enzyme in prostaglandins (PGs) biosynthesis. Previous studies indicate that COX-2, one of the isoforms of COX, is highly expressed in colon cancers and plays a key role in colon cancer carcinogenesis. Thus, searching for novel transcription factors regulating COX-2 expression will facilitate drug development for colon cancer. In this study, we identified XRCC5 as a binding protein of the COX-2 gene promoter in colon cancer cells with streptavidin-agarose pulldown assay and mass spectrometry analysis, and found that XRCC5 promoted colon cancer growth through modulation of COX-2 signaling. Knockdown of XRCC5 by siRNAs inhibited the growth of colon cancer cells in vitro and of tumor xenografts in a mouse model in vivo by suppressing COX-2 promoter activity and COX-2 protein expression. Conversely, overexpression of XRCC5 promoted the growth of colon cancer cells by activating COX-2 promoter and increasing COX-2 protein expression. Moreover, the role of p300 (a transcription co-activator) in acetylating XRCC5 to co-regulate COX-2 expression was also evaluated. Immunofluorescence assay and confocal microscopy showed that XRCC5 and p300 proteins were co-located in the nucleus of colon cancer cells. Co-immunoprecipitation assay also proved the interaction between XRCC5 and p300 in nuclear proteins of colon cancer cells. Cell viability assay indicated that the overexpression of wild-type p300, but not its histone acetyltransferase (HAT) domain deletion mutant, increased XRCC5 acetylation, thereby up-regulated COX-2 expression and promoted the growth of colon cancer cells. In contrast, suppression of p300 by a p300 HAT-specific inhibitor (C646) inhibited colon cancer cell growth by suppressing COX-2 expression. Taken together, our results demonstrated that XRCC5 promoted colon cancer growth by cooperating with p300 to regulate COX-2 expression, and suggested that the XRCC5/p300/COX-2 signaling pathway was a potential target in the treatment of colon cancers.

User preference for a portable syringe pump for iloprost infusion

Purpose

Administration of intravenous iloprost – a first-line European League Against Rheumatism (EULAR)-recommended choice for the treatment of scleroderma (SSc)-related digital vasculopathy – requires repeated treatment cycles of 6 hours per day in a hospital setting. During the infusion, patient mobility is considerably restricted due to the size and fixity of traditional syringe pumps. The aim of this study was to evaluate the satisfaction level of patients and nurses, after the introduction of a new portable syringe pump (Infonde^®, Italfarmaco S.p.A., Milan, Italy) at the Department of Rheumatology, Magenta Hospital, Milan, Italy.

Patients and methods

Thirty-four consecutive SSc patients receiving stable therapy with iloprost, previously administered with a fixed pump, were treated using the portable Infonde^® pump. Patients (n=34) and nurses (n=4) were asked to answer a nine- and six-item questionnaire, respectively, to assess the satisfaction of the administration comparing the new device versus the previous one. The health care staff of the ward developed the questionnaire, and the response scores ranged from 0 (fixed device better) to 10 (portable device better); thus a score >5 indicates a preference for Infonde^®.

Results

Patients’ answers indicated a preference towards the new portable syringe pump, versus the previous fixed pump. Questionnaires administered to patients generated a total of 306 responses, with over 95% of the responses in the range 8–10, of which 89% had a score equal to 10. The responses of nurses showed a score equal to 10 in 100% cases. No significant adverse events were recorded, indicating no change in the tolerability profile of the drug.

Conclusion

Iloprost administration with Infonde^® pump was preferred by both patients and health care professionals, and was well tolerated. The possibility to perform daily activities and the freedom of movement suggest a positive impact of Infonde^® on the treatment, with a potential favorable effect on the quality of life of patients during the many hours spent receiving the infusion.

Role of RANTES and its receptor in gastric cancer metastasis

This study examined the role of regulated upon activation normal T cell expressed and secreted (RANTES) and its receptor C-C chemokine receptor type 5 (CCR5) in gastric cancer metastasis and the associated mechanism. The expression of RANTES and CCR5 was detected by using immunohistochemical staining and Western blotting in the gastric cancer tissues obtained from 60 gastric cancer patients with or without lymph node metastasis (n=30 in each). The results showed that the expression levels of RANTES and CCR5 were higher in gastric cancer with lymph node metastasis than in that without metastasis (P<0.05). The expression levels of RANTES in 30 lymph nodes with cancerous invasion were higher than in 30 normal lymph nodes (P<0.05). Chemotactic test revealed that the number of migrating gastric cancer cells (n=295.0 ± 54.6) induced by the protein of cancer-invading lymph nodes was greater than that by the protein mixture from cancer-invading lymph nodes and RANTES antibody (n=42.5 ± 11.6) (P<0.05). RT-PCR showed that the expression levels of the main Th1 cytokines (IL-2, Γ-IFN) were lower in gastric cancer with lymph node metastasis (2.22 ± 0.90, 3.26 ± 1.15 respectively) than in that without metastasis (3.07 ± 1.67, 4.77 ± 1.52 respectively) (P<0.05), but the expression level of the main Th 2 cytokine (IL-10) was higher in gastric cancer with lymph nodes metastasis (6.06 ± 2.04) than in that without metastasis (4.88 ± 1.87) (P<0.05). It was concluded that RANTES and its receptor CCR5 may contribute to gastric cancer metastasis through influencing the balance of Th1/Th2. RANTES and CCR5 may become a marker of gastric cancer metastasis.

Ganoderma lucidum polysaccharides antagonize the suppression on lymphocytes induced by culture supernatants of B16F10 melanoma cells

Objectives

Tumour cells produce factors such as interleukin 10 (IL-10), transforming growth factor β1 (TGF-β1) and vascular endothelial growth factor (VEGF) that suppress the function of immune cells or induce apoptosis of immune cells. One of the most important goals of tumour immunotherapy is to antagonize this suppression on immune cells. Ganoderma lucidum polysaccharides (Gl-PS) may have this potential. The purpose of this study was to determine the antagonistic effects of Gl-PS on the suppression induced by B16F10 melanoma cell culture supernatant (B16F10-CS) on lymphocytes.

Methods

Gl-PS was used on lymphocytes incubated with B16F10-CS. Enzyme-linked immunosorbent assay was used to determine the levels of IL-10, TGF-β1 and VEGF in B16F10-CS. The MTT assay was used to determine the proliferation of lymphocytes. Immunocytochemistry and Western blot assay were used to determine perforin and granzyme B production in lymphocytes.

Key findings

There were elevated levels of IL-10, TGF-β1 and VEGF in B16F10-CS. The lymphocyte proliferation, and perforin and granzyme B production in lymphocytes after induction with phytohemagglutinin, as well as lymphocyte proliferation in the mixed lymphocyte reaction, were suppressed by B16F10-CS. This suppression was fully or partially antagonized by Gl-PS.

Conclusions

B16F10-CS suppressed lymphocyte proliferation and perforin and granzyme B production in lymphocytes after induction with phytohemagglutinin, as well as lymphocyte proliferation in the mixed lymphocyte reaction. This suppression may be associated with elevated levels of immunosuppressive IL-10, TGF-β1 and VEGF in B16F10-CS. Gl-PS had antagonistic effects on the immunosuppression induced by B16F10-CS, suggesting the potential for Gl-PS in cancer immunotherapy.

Non-Steroidal Anti-Inflammatory Drugs in the Carcinogenesis of the Gastrointestinal Tract

It is estimated that underlying infections and inflammatory responses are linked to 15–20% of all deaths from cancer worldwide. Inflammation is a physiologic process in response to tissue damage resulting from microbial pathogen infection, chemical irritation, and/or wounding. Tissues injured throughout the recruitment of inflammatory cells such as macrophages and neutrophils, generate a great amount of growth factors, cytokines, and reactive oxygen and nitrogen species that may cause DNA damage that in turn predisposes to the transformation from chronic inflammation to neoplasia. Cyclooxygenase (COX), playing a key role in cell homeostasis, angiogenesis and tumourigenesis, may represent the link between inflammation and cancer. Currently COX is becoming a pharmacological target for cancer prevention and treatment.

Countering tumor-induced immunosuppression during immunotherapy for pancreatic cancer

BACKGROUND

Vaccines for pancreatic cancer have been challenged by a number of factors, especially the immunosuppressive microenvironment within the tumor that allows for escape from immune surveillance.

OBJECTIVE/METHODS

We sought to identify results that define mechanisms of pancreatic-cancer-associated immunosuppression and strategies that might be useful to overcome them thereby resulting in effective immune responses to cancer vaccines capable of deleting pancreatic cancer cells.

RESULTS/CONCLUSION

Immunosuppressive tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSC), and regulatory T cells (Treg) reside in tumors, and their products along with tumor derived products (such as VEGF, TGFbeta and IL-10), create a microenvironment that counters immune activation and attack. Immunotherapy with cancer vaccines must include strategies to modulate these immunosuppressive cell types and tumor byproducts. Clinical trials are beginning to test these strategies.

Inhaled iloprost suppresses the cardinal features of asthma via inhibition of airway dendritic cell function

Inhalation of iloprost, a stable prostacyclin (PGI(2)) analog, is a well-accepted and safe treatment for pulmonary arterial hypertension. Although iloprost mainly acts as a vasodilator by binding to the I prostanoid (IP) receptor, recent evidence suggests that signaling via this receptor also has antiinflammatory effects through unclear mechanisms. Here we show in a murine model of asthma that iloprost inhalation suppressed the cardinal features of asthma when given during the priming or challenge phase. As a mechanism of action, iloprost interfered with the function of lung myeloid DCs, critical antigen-presenting cells of the airways. Iloprost treatment inhibited the maturation and migration of lung DCs to the mediastinal LNs, thereby abolishing the induction of an allergen-specific Th2 response in these nodes. The effect of iloprost was DC autonomous, as iloprost-treated DCs no longer induced Th2 differentiation from naive T cells or boosted effector cytokine production in primed Th2 cells. These data should pave the way for a clinical effectiveness study using inhaled iloprost for the treatment of asthma.

Global Tumor RNA Expression in Early Establishment of Experimental Tumor Growth and Related Angiogenesis following Cox-Inhibition Evaluated by Microarray Analysis

Altered expression of COX-2 and overproduction of prostaglandins, particularly prostaglandin E2, are common in malignant tumors. Consequently, non-steroidal anti-inflammatory drugs (NSAIDs) attenuate tumor net growth, tumor related cachexia, improve appetite and prolong survival. We have also reported that COX-inhibition (indomethacin) interfered with early onset of tumor endothelial cell growth, tumor cell proliferation and apoptosis. It is however still unclear whether such effects are restricted to metabolic alterations closely related to eicosanoid pathways and corresponding regulators, or whether a whole variety of gene products are involved both up- and downstream effects of eicosanoids. Therefore, present experiments were performed by the use of an in vivo, intravital chamber technique, where micro-tumor growth and related angiogenesis were analyzed by microarray to evaluate for changes in global RNA expression caused by indomethacin treatment.

Indomethacin up-regulated 351 and down-regulated 1852 genes significantly (p < 0.01); 1066 of these genes had unknown biological function. Genes with altered expression occurred on all chromosomes.

Our results demonstrate that indomethacin altered expression of a large number of genes distributed among a variety of processes in the carcinogenic progression involving angiogenesis, apoptosis, cell-cycling, cell adhesion, inflammation as well as fatty acid metabolism and proteolysis. It remains a challenge to distinguish primary key alterations from secondary adaptive changes in transcription of genes altered by cyclooxygenase inhibition.

Mechanisms of the self/non-self-survey in the defense against cancer: Potential for chemoprevention?

When compared to a reference population, several large epidemiological studies with long-term follow-up have reported a three- to five-fold increased risk of neoplasia amongst patients who have received organ transplants, with an incidence curve that rises in a linear fashion with time. The relationship between the immune system and cancer is complex. The ability to discriminate "self" from "non-self" is one of the central roles of the immune system. Since tumors arise from transformation of host cells, it is not surprising that some aspects of tumor immunity resemble autoimmunity. The immune response to tumors shares aspects of both self- and non-self-immune recognition. What accounts for the apparent failure of immunity? In this review article, we address the role of the self/non-self-survey in the immune response to tumors, we describe mechanisms of immune surveillance against tumor cells, and we discuss models of ignorance, tolerance and tumor evasion of the immune response. The overall aim of the article is to demonstrate the scope for prevention of cancer in individuals at increased risk of developing malignancy due to immune compromise. Interventional strategies may involve the use of pro-differentiation agents such as retinoids, modifiers of polyamine biosynthesis or inhibitors of cyclooxygenase isozymes.

The role of prostaglandins and other eicosanoids in the gastrointestinal tract

Nonsteroidal anti-inflammatory drugs (NSAIDs) are generally prescribed to ameliorate symptoms associated with acute pain and chronic inflammatory diseases such as arthritis. Recent epidemiologic studies and clinical trials indicate that use of NSAIDs and cyclooxygenase (COX)-2 selective inhibitors are associated with a reduced risk of certain malignancies, especially gastrointestinal cancer. The cyclooxygenase enzymes are the best known targets of NSAIDs; this diverse class of compounds blocks conversion of arachidonic acid to prostanoids. Prostaglandins and other eicosanoids derived from COX-1 and COX-2 are involved in a variety of physiologic and pathologic processes in the gastrointestinal tract. Recent efforts to identify the molecular mechanisms by which COX-2-derived prostanoids exert their proneoplastic effects have provided a rationale for the possible use of NSAIDs alone or in a combination with conventional or experimental anticancer agents for the treatment or prevention of gastrointestinal cancers.

Decrease in circulating endothelial cell adhesion molecule and thrombomodulin levels during oral iloprost treatment in rheumatoid arthritis patients: preliminary results

OBJECTIVE

Rheumatoid arthritis is a chronic inflammatory autoimmune disease with proinflammatory cytokines involved in its pathogenesis. Recently in vitro as well as in vivo studies have shown that iloprost, a stable prostacyclin analogue, can reduce the release of these cytokines. This study was performed to further investigate the anti-inflammatory effects of iloprost by determining plasma adhesion molecules as markers of endothelial cell activation, and plasma thrombomodulin as a parameter of endothelial cell injury in patients with rheumatoid arthritis receiving oral iloprost therapy.

METHODS

Plasma thrombomodulin levels and the values of the plasma adhesion molecules VCAM-1 (vascular cell adhesion molecule 1), E-selectin (CD62E), and ICAM-1 (intercellular adhesion molecule 1, CD 54) were measured by ELISA during a 7-day period of treatment with orally-administered iloprost in 14 patients with active rheumatoid arthritis. Finally, the same parameters were determined at the end of the observation period (1 week after the end of therapy). In addition, the disease activity was measured using the DAS (disease activity score) as well as the patients' self-assessed pain severity, and correlated with the changes of plasma adhesion molecule and thrombomodulin levels.

RESULTS

The plasma levels of all three adhesion molecules as well as of thrombomodulin significantly decreased under therapy with oral iloprost. After 1 week (day 7 of therapy), the mean percent changes from day 0 were -20.1% for VCAM-1 (p = 0.008), -21.2 for ICAM-1 (p = 0.003), -24.6% for E-selectin (p = 0.001), and -21.7% for thrombomodulin (p = 0.003). This decrease lasted up to 1 week after the end of therapy in the case of VCAM-1 (p = 0.023) and ICAM-1 (p = 0.001). Further analysis of the results revealed additional significant correlations between different parameters of clinical disease activity, thrombomodulin and adhesion molecules.

CONCLUSION

This study showed hints towards clinical effects in patients with rheumatoid arthritis receiving oral iloprost therapy. Pathophysiologically, the decrease of adhesion molecules points at an immunomodulating effect of iloprost. The observed thrombomodulin-lowering effect of iloprost may indicate stabilisation of endothelial cell function by diminishing endothelial cell injury.

Prostacyclin and its analogues in the treatment of pulmonary hypertension

Prostacyclin and its analogues (prostanoids) are potent vasodilators and possess antithrombotic and antiproliferative properties. All of these properties help to antagonize the pathological changes that take place in the small pulmonary arteries of patients with pulmonary hypertension. Indeed, several prostanoids have been shown to be efficacious to treat pulmonary hypertension, while the main mechanism underlying the beneficial effects remains unknown. There are indications of beneficial combination effects of prostaglandins and phosphodiesterase inhibitors and endothelin receptor antagonists. This speaks in favor of combination therapies for pulmonary hypertension in the future. The mode of application of prostanoids used in randomized controlled studies has been quite variable: continuous i.v. infusion of prostacyclin, continuous s.c. infusion of treprostinil, p.o. application of beraprost, and inhaled application of iloprost. In addition, the applied doses were quite different, ranging from 0.25 ng/kg/min for inhaled iloprost to 30-50 ng/kg/min for i.v. prostacyclin. While the principal pharmacological properties of all prostanoids are very similar due to a main action on IP receptors, there are considerable differences in pharmacokinetics and metabolism, with half-lives of 2 min for prostacyclin and about 34 min for treprostinil for i.v. infused drugs and half-lives of about 85 min for s.c. infused treprostinil. In addition, the adverse effects largely depend on the doses used and the mode of application, although there is great variability between subjects. It remains to be determined which patients will profit most from which substance (or combination) and mode of application.

Prolonged lipopolysaccharide inhibits leukotriene synthesis in peritoneal macrophages: mediation by nitric oxide and prostaglandins

Resident rat peritoneal macrophages synthesize a variety of prostanoids and leukotrienes from arachidonic acid. Overnight treatment with lipopolysaccharide (LPS) induces the synthesis of cyclooxygenase-2 (COX-2) and an altered prostanoid profile that emphasizes the preferential conversion of arachidonic acid to prostacyclin and prostaglandin E2. In these studies, we report that exposure to LPS also caused a strong suppression of 5-lipoxygenase but not 12-lipoxygenase activity, indicated by the inhibition of synthesis of both leukotriene B4 and 5-hydroxyeicosatetraenoic acid (5-HETE), but not of 12-HETE. Inhibition of 5-lipoxygenase activity by LPS was both time- and dose-dependent. Treatment of macrophages with prostaglandin E2 partially inhibited leukotriene synthesis, and cyclooxygenase inhibitors partially blocked the inhibition of leukotriene generation in LPS-treated cells. In addition to COX-2, nitric oxide synthase (NOS) was also induced by LPS. Treatment of macrophages with an NO donor mimicked the ability of LPS to significantly reduce leukotriene B4 synthesis. Inhibition of NOS activity in LPS-treated cells blunted the suppression of leukotriene synthesis. Inhibition of both inducible NOS and COX completely eliminated leukotriene suppression. Finally, macrophages exposed to prolonged LPS demonstrated impaired killing of Klebsiella pneumoniae and the combination of NOS and COX inhibitors restored killing to the control level. These results indicate that prolonged exposure to LPS severely inhibits leukotriene production via the combined action of COX and NOS products. The shift in mediator profile, to one that minimizes leukotrienes and emphasizes prostacyclin, prostaglandin E2 and NO, provides a signal that reduces leukocyte function, as indicated by impaired killing of Gram-negative bacteria.

In vitro effects of eicosanoids derived from different 20-carbon fatty acids on T helper type 1 and T helper type 2 cytokine production in human whole-blood cultures

BACKGROUND

Different series prostaglandins (PGs) and leukotrienes (LTs) are synthesized from different 20 carbon fatty acid precursors. The effects of the different series of PGs and LTs on production of T helper type 1 (Th1) and Th2 cytokines by human cells are not well established.

OBJECTIVE

To characterize the influence of PGs and LTs produced from different fatty acid precursors on the Th1 and Th2 cytokine profile in mitogen-stimulated human whole-blood cultures.

METHODS

Blood from healthy adult males was diluted and cultured with concanavalin A in the presence or absence of a range of concentrations of various PGs or LTs. Cytokine concentrations in culture supernatants were analysed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

PGE1, PGE2 and PGE3 significantly and dose-dependently decreased the concentrations of the Th1 cytokines IL-2 and IFN-gamma by up to 50% and 70%, respectively. The three PGs exhibited similar potency towards IFN-gamma production. At the highest concentration used (10-6 m) PGE1, but not PGE2 or PGE3, increased the concentration of the Th2 cytokine IL-4 by about 70%. IL-10 production was not affected by PGs. The ratio of the concentrations of IFN-gamma to IL-4 was significantly decreased at PGE concentrations of 10-7 and 10-6 M with all three PGEs having similar effects. LTB4, LTC4 and LTC5 did not significantly affect production of the cytokines studied.

CONCLUSION

PGE produced from different fatty acids significantly decrease Th1 cytokine production resulting in a shift in the Th1, Th2 balance in favour of a Th2 response. PGE produced from different fatty acid precursors are equipotent in their effects on human T lymphocytes. Thus, although changes in the pattern of dietary fatty intakes may contribute to the increased prevalence of atopic disease, this would probably not be mediated through substitution of one PGE with another from a different series. It may, however, be mediated through a change in the total amount of PGE produced at the site of antigen presentation.

Epidermal growth factor receptors and cyclooxygenase-2 in the pathogenesis of non-small cell lung cancer: potential targets for chemoprevention and systemic therapy

The epidermal growth factor receptor (EGFR) is part of a family of plasma membrane receptor tyrosine kinases that control many important cellular functions, from growth and proliferation to cell death. Cyclooxygenase (COX)-2 is an enzyme which catalyses the conversion of arachidonic acid to prostagladins and thromboxane. It is induced by various inflammatory stimuli, including the pro-inflammatory cytokines, Interleukin (IL)-1beta, Tumour Necrosis Factor (TNF)-alpha and IL-2. Both EGFR and COX-2 are over-expressed in non-small cell lung cancer (NSCLC) and have been implicated in the early stages of tumourigenesis. This paper considers their roles in the development and progression of lung cancer, their potential interactions, and reviews the recent progress in cancer therapies that are directed toward these targets. An increasing body of evidence suggests that selective inhibitors of both EGFR and COX-2 are potential therapeutic agents for the treatment of NSCLC, in the adjuvant, metastatic and chemopreventative settings.

Biological effect of the Planktothrix sp. FP1 cyanobacterial extract

Cyanobacteria are common and potentially harmful inhabitants of freshwater and marine environments worldwide. Some waterbloom-forming cyanobacteria are toxic and they may cause animal death and adversely affect human health. A filamentous freshwater cyanobacterium, Planktothrix sp. FP1, was found to be responsible for a toxic algal bloom in Lake Varese (Italy) during August of 1997. In the present study, the biological effects of the Planktothrix sp. FP1 cell extract on Xenopus embryos and on human Peripheral Blood Mononuclear Cells (PBMC) were investigated. FETAX (Frog Embryo Teratogenesis Assay-Xenopus) showed that the cyanobacterial extract had no teratogenic potential, though embryotoxicity was detected (LC(50) 2.944g/l wet weight). The same extract inhibited the proliferation of PBMC stimulated in vitro by phytohemagglutinin (PHA), and strongly interfered with the production of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma).

Chronic immune activation and inflammation in the pathogenesis of AIDS and cancer

Infection with the human immunodeficiency virus (HIV) invariably leads to the development of acquired immunodeficiency syndrome (AIDS) in most infected humans, yet does so rarely, if at all, in HIV-infected chimpanzees. The differences between the two species are not due to differences in cellular receptors or an inability of the chimpanzee to be infected, but rather to the lack of pan-immune activation in the infected primate. This results in reduced apoptotic death in CD4+ T-helper lymphocytes and a lower viral load. In humans the degree of chronic immune activation correlates with virus load and clinical outcome with high immune activation leading to high viral loads and the more rapid progression to AIDS and death. The type of immune perturbation seen in HIV-associated AIDS is similar to that of chronic graft-versus-host disease (GVHD) where reduced cell-mediated immune (CMI) responses occur early in the course of the disease and where humoral responses (HI) predominate. A reduced CMI response occurs in a number of chronic infectious diseases, including tuberculosis and leishmaniasis. More recently, it has become increasingly apparent that the CMI response is suppressed in virtually all malignant diseases, including melanoma and colorectal and prostate cancer. This raises the possibility that, as the malignant process develops, the cancer cells evolve to subvert the CMI response. Moreover, the reduced CMI response seen in colorectal cancer (CRC) patients is completely reversed following curative surgery strongly supporting the hypothesis that CRC can suppress the systemic immune response. Wound healing, ovulation, embryo implantation, and fetal growth are all associated with suppressed CMI and neovascularization (the formation of new blood vessels) or angiogenesis (the formation of new blood vessels from an existing vasculature). If unresolved, wound healing results in chronic inflammation, which can give rise to the phenomenon of "scar cancers." Indeed all the chronic inflammatory conditions known to be associated with the subsequent development of malignant disease, including chronic obstructive airway disease (COPD), ulcerative colitis (UC), and asbestosis, give rise to similar proangiogenic, suppressed CMI, and HI-predominant environments. In keeping with this CMI-associated cytokines such as interleukin (IL)-2 and interferon (IFN)-gamma tend to be antiangiogenic, whereas HI cytokines such as IL-6 tend to be proangiogenic. Furthermore, chronic immune activation leads to the synthesis and release of factors such as macrophage inflammatory protein (MIP)-1 that inhibit apoptosis through suppression of p53 activity. The "Golden Triangle" of suppressed CMI, angiogenesis, and reduced apoptosis would provide the ideal environment for the serial mutations to occur that are required for the development of malignant disease. If the observed association is relevant to carcinogenesis, then treatments aimed at reducing the components of these inflammatory conditions may be useful both in the setting of chemoprevention and the therapeutic management of established disease.

Elevated expression of cyclooxygenase-2 contributes to immune dysfunction in a murine model of trauma

BACKGROUND

Cyclooxygenase-2 (Cox-2), the inducible form of Cox, is a rate-limiting enzyme in the synthesis of prostaglandins (PGs). Prostaglandin E2 (PGE2) and other eicosanoids possess immunosuppressive properties. Previously, traumatic injury was found to stimulate the synthesis of PGs and cause immune dysfunction. In this study a murine model was used to determine the effect of trauma on the expression of Cox-2 in macrophages and to elucidate the role of Cox-2 in trauma-induced immune dysfunction.

METHODS

Mice were randomized to control or trauma (femur fracture plus 40% blood volume hemorrhage) groups. One, 4, and 7 days after injury, splenic macrophages were isolated and assayed for expression of Cox-2 and production of PGE2. In addition, the effect of pharmacologically inhibiting Cox-2 or knocking out the Cox-2 gene on trauma-induced suppression of splenocyte mitogenesis was determined.

RESULTS

Trauma led to increased expression of Cox-2, enhanced synthesis of PGE2, and suppressed splenocyte mitogenesis. Both pharmacologic inhibition and genetic deletion of Cox-2 abrogated trauma-mediated suppression of splenocyte mitogenesis.

CONCLUSIONS

These experiments link trauma-induced increases in Cox-2 expression and PGE2 production to reduced immune function. Cox-2 represents a potential pharmacologic target to prevent or reverse trauma-induced immunosuppression.

Chronic immune activation and inflammation as the cause of malignancy

Several chronic infections known to be associated with malignancy have established oncogenic properties. However the existence of chronic inflammatory conditions that do not have an established infective cause and are associated with the development of tumours strongly suggests that the inflammatory process itself provides the prerequisite environment for the development of malignancy. This environment includes upregulation of mediators of the inflammatory response such as cyclo-oxygenase (COX)-2 leading to the production of inflammatory cytokines and prostaglandins which themselves may suppress cell mediated immune responses and promote angiogenesis. These factors may also impact on cell growth and survival signalling pathways resulting in induction of cell proliferation and inhibition of apoptosis. Furthermore, chronic inflammation may lead to the production of reactive oxygen species and metabolites such as malondialdehyde within the affected cells that may in turn induce DNA damage and mutations and, as a result, be carcinogenic. Here it is proposed that the conditions provided by a chronic inflammatory environment are so essential for the progression of the neoplastic process that therapeutic intervention aimed at inhibiting inflammation, reducing angiogenesis and stimulating cell mediated immune responses may have a major role in reducing the incidence of common cancers.

Novel mode of action of iloprost: in vitro down-regulation of endothelial cell adhesion molecules

Iloprost is a stable prostacyclin analog commonly employed in the treatment of peripheral vascular disease and also indicated in the treatment of patients affected by systemic sclerosis (SSc) in the presence of severe Raynaud's phenomenon (RP). Several mechanisms of action of the drug other than vasodilation and antiplatelet effect have been demonstrated that may be involved in the exertion of its clinical efficacy. Aim of the present study was to investigate whether iloprost down-regulated lymphocyte adhesion to endothelium through a modulation of adhesion molecule expression on the surface of endothelial cells. In the presence of iloprost, both lymphocyte adhesion and IL-1 stimulated expression of ICAM-1 and ELAM-1 exhibited a significant reduction, while unstimulated adhesion molecule expression was not significantly affected. Our results confirm that iloprost is able to down-regulate lymphocyte adhesion to endothelial cells and indicate that endothelium itself could be target of iloprost administration. Attenuation of the inflammatory response through modulation of cellular interactions could be suggested as a potential mechanism of action of iloprost, when used in the treatment of pathological conditions characterized by endothelial activation.

An essential role of the nuclear factor of activated T cells in the regulation of the expression of the cyclooxygenase-2 gene in human T lymphocytes

We have previously reported that transcriptional induction of cyclooxygenase-2 (COX-2) isoenzyme occurs early after T cell receptor triggering, suggesting functional implications of cyclooxygenase activity in this process. Here, we identify the cis-acting elements responsible for the transcriptional activation of this gene in human T lymphocytes. COX-2 promoter activity was induced upon T cell activation both in primary resting T lymphocytes and in Jurkat cells. This induction was abrogated by inhibition of calcineurin phosphatase with the immunosuppressive drug cyclosporin A, whereas expression of an active calcineurin catalytic subunit enhanced COX-2 transcriptional activation. Moreover, cotransfection of nuclear factor of activated T cells (NFAT) wild type protein transactivated COX-2 promoter activity. Conversely, dominant negative mutants of NFATc or c-Jun proteins inhibited COX-2 induction. Electrophoretic mobility shift assays and site-directed mutagenesis allowed the identification of two regions of DNA located in the positions -117 and -58 relative to the transcriptional start site that serves as NFAT recognition sequences. These results emphasize the central role that the Ca(2+)/calcineurin pathway plays in COX-2 transcriptional regulation in T lymphocytes pointing to NFAT/activator protein-1 transcription factors as essential for COX-2 promoter regulation in these cells.

The relationship between angiogenesis and the immune response in carcinogenesis and the progression of malignant disease

Recent studies have demonstrated that angiogenesis and suppressed cell-mediated immunity (CMI) play a central role in the pathogenesis of malignant disease facilitating tumour growth, invasion and metastasis. In the majority of tumours, the malignant process is preceded by a pathological condition or exposure to an irritant which itself is associated with the induction of angiogenesis and/or suppressed CMI. These include: cigarette smoking, chronic bronchitis and lung cancer; chronic oesophagitis and oesophageal cancer; chronic viral infections such as human papilloma virus and ano-genital cancers, chronic hepatitis B and C and hepatocellular carcinoma, and Epstein-Barr virus (EBV) and lymphomas; chronic inflammatory conditions such as Crohn's disease and ulcerative colitis and colorectal cancer; asbestos exposure and mesothelioma and excessive sunlight exposure/sunburn and malignant melanoma. Chronic exposure to growth factors (insulin-like growth factor-I in acromegaly), mutations in tumour suppressor genes (TP53 in Li Fraumeni syndrome) and long-term exposure to immunosuppressive agents (cyclosporin A) may also give rise to similar environments and are associated with the development of a range of solid tumours. The increased blood supply would facilitate the development and proliferation of an abnormal clone or clones of cells arising as the result of: (a) an inherited genetic abnormality; and/or (b) acquired somatic mutations, the latter due to local production and/or enhanced delivery of carcinogens and mutagenic growth factors. With progressive detrimental mutations and growth-induced tumour hypoxia, the transformed cell, to a lesser or greater extent, may amplify the angiogenic process and CMI suppression, thereby facilitating further tumour growth and metastasis. There is accumulating evidence that long-term treatment with cyclo-oxygenase inhibitors (aspirin and indomethacin), cytokines such as interferon-alpha, anti-oestrogens (tamoxifen and raloxifene) and captopril significantly reduces the incidence of solid tumours such as breast and colorectal cancer. These agents are anti-angiogenic and, in the case of aspirin, indomethacin and interferon-alpha have proven immunomodulatory effects. Collectively these observations indicate that angiogenesis and suppressed CMI play a central role in the development and progression of malignant disease.

Decreased production of interleukin-6 and prostaglandin E2 associated with inhibition of delta-5 desaturation of omega6 fatty acids in mice fed safflower oil diets supplemented with sesamol

The differences in the immune responses in mice fed sesame oil diets and those fed sesamin may be attributed to the presence of other lignans in the non-fat portion of the oil. The fatty acid composition (mean +/- SD mol. %) of liver membrane phospholipids and the levels of endotoxin-induced prostaglandin (PG) E2, interleukin (IL)-6, IL-10, IL-12 and tumor necrosis factor (TNF)-alpha were determined in mice fed diets supplemented with 5% safflower oil (SO) in the absence or presence of 1% sesamol. The levels of dihomo-gamma-linolenic acid (20:3omega6) were markedly higher (P<0.025) in the livers from mice fed sesamol supplemented SO diets (1.6 +/- 0.1) compared to the controls (1.4 +/- 0.1). These data suggest that sesamol or its metabolite could inhibit the in vivo delta-5 desaturation of omega6 fatty acids. Further, in animals fed sesamol supplemented SO diets, the levels of PGE2 (228 +/- 41 pg/ml) were markedly lower (P<0.01) compared to those fed SO diet alone (1355 +/- 188 pg/ml). Concomitantly, the concentrations of IL-6 were also lower (P<0.01) in mice fed sesamol diet (63 +/- 11 ng/ml) compared to the controls (143 +/- 22 ng/ml). A marked reduction in the levels of PGE2 in animals fed sesamol diets suggests that sesamol or its metabolite could inhibit the activity of cyclooxygenase enzyme.

Induction of Cyclooxygenase-2 on Activated T Lymphocytes: Regulation of T Cell Activation by Cyclooxygenase-2 Inhibitors

Cyclooxygenase (COX), known to exist in two isoforms, COX-1 and COX-2, is a key enzyme in prostaglandin synthesis and the target for most nonsteroidal anti-inflammatory drugs. In this study, we show that human T lymphocytes express the COX-2 isoenzyme. COX-2 mRNA and protein were induced in both Jurkat and purified T cells stimulated by TCR/CD3 or PMA activation. COX-2 mRNA was induced very early after activation and superinduced by protein synthesis inhibitors, whereas it was inhibited by the immunosuppressive drug cyclosporin A, identifying it as an early T cell activation gene. Interestingly, treatment with COX-2-specific inhibitors such as NS398 or Celecoxib severely diminished early and late events of T cell activation, including CD25 and CD71 cell surface expression, IL-2, TNF-α, and IFN-γ production and cell proliferation, but not the expression of CD69, an immediate early gene. COX-2 inhibitors also abolished induced transcription of reporter genes driven by IL-2 and TNF-α promoters. Moreover, induced transcription from NF-κB- and NF-AT-dependent enhancers was also inhibited. These results may have important implications in anti-inflammatory therapy and open a new field on COX-2-selective nonsteroidal anti-inflammatory drugs as modulators of the immune activation.