Beneficial impact of cathelicidin on hypersensitivity pneumonitis treatment-In vivo studies.

Cathelicidin (CRAMP) is a defence peptide with a wide range of biological responses including antimicrobial, immunomodulatory and wound healing. Due to its original properties the usefulness of CRAMP in the treatment of pulmonary fibrosis was assessed in a murine model of hypersensitivity pneumonitis (HP). The studies were conducted on mouse strain C57BL/6J exposed to a saline extract of Pantoea agglomerans cells (HP inducer). Cathelicidin was administered in the form of an aerosol during and after HP development. Changes in the composition of immune cell populations (NK cells, macrophages, lymphocytes: Tc, Th, Treg, B), were monitored in lung tissue by flow cytometry. Extracellular matrix deposition (collagens, hydroxyproline), the concentration of cytokines involved in inflammatory and the fibrosis process (IFNγ, TNFα, TGFß1, IL1ß, IL4, IL5, IL10, IL12α, IL13) were examined in lung homogenates by the ELISA method. Alterations in lung tissue morphology were examined in mouse lung sections stained with haematoxylin and eosin as well as Masson trichrome dyes. The performed studies revealed that cathelicidin did not cause any negative changes in lung morphology/structure, immune cell composition or cytokines production. At the same time, CRAMP attenuated the immune reaction induced by mice chronic exposure to P. agglomerans and inhibited hydroxyproline and collagen deposition in the lung tissue of mice treated with bacteria extract. The beneficial effect of CRAMP on HP treatment was associated with restoring the balance in quantity of immune cells, cytokines production and synthesis of extracellular matrix components. The presented study suggests the usefulness of cathelicidin in preventing lung fibrosis; however, cathelicidin was not able to reverse pathological changes completely.

Colon cancer-derived conditioned medium induces differentiation of THP-1 monocytes into a mixed population of M1/M2 cells.

Macrophages play an important role in the immune response and in the maintenance of tissue homeostasis. It is well known that many tumors recruit monocytes from circulation and influence their differentiation, mainly into suppressive M2-like subsets. Since there are contradictory data concerning the importance of macrophages for colon cancer progression, we used in our experiments four colon cancer cell lines representing different stages of tumor development (HT29, LS180, SW948, SW620). An acute monocytic leukemia cell line THP-1 was used as a human model of monocytes. Our work revealed that conditioned medium from the tumor cell lines induced activation and differentiation of THP-1 cells. The changes involved increased expression of CD68, a macrophage differentiation marker. Moreover, we also observed increased expression of CD206 and CD163, which are widely considered as markers of tumor-associated macrophages. The tumor-derived conditioned medium decreased the proliferation of THP-1 cells and blocked their cell cycle at the G1 stage. The tumor-conditioned medium also upregulated the production of several cytokines and chemokines characteristic of both M1 and M2 subsets and induced the expression of important pro-angiogenic factors, vascular endothelial growth factor, and matrix metalloproteinase-9 in THP-1 cells. Moreover, the tumor-conditioned medium induced the expression of galectin-3, which is implicated in malignant transformation, and indoleamine 2,3-dioxygenase, that is, a key enzyme of the kynurenine pathway. Our data suggest that tumor cells can actively influence the phenotype of monocytes and switch their differentiation into a population of non-adherent mixed M1 and M2 cells. These preliminary studies suggest that colon cancer cells produce soluble factors that influence monocyte differentiation, most probably into suppressive subsets. These data provide a better understanding of the influence of colon cancer on polarization of monocytes.

Riluzole Inhibits Proliferation, Migration and Cell Cycle Progression and Induces Apoptosis in Tumor Cells of Various Origins.

BACKGROUND: Regardless of contemporary improvements in cancer treatment, the results of drug treatment are not always efficacious. Thus, the development of novel approaches that affect cancer cell-specific metabolic pathways is needed. Since much evidence has shown that tumor cell proliferation and motility are stimulated by glutamate via activation of its receptors, use of antagonists to these receptors may be the key to control cancer cell progression. Riluzole noncompetitive metabotropic glutamate receptor 1 (mGluR1) antagonist, commonly used to treat patients with amyotrophic lateral sclerosis (ALS), has shown some antineoplastic properties against melanoma, breast and prostate cancer. Yet little is known about its molecular mode of action. AIMS: The current study aims at evaluating the abilities of Riluzole to inhibit proliferation of several cancer cell lines, as well as resolve the mechanism of its action. METHOD: We demonstrated antiproliferative and antimigrative properties of Riluzole in rhabdomyosarcomamedulloblastoma, neuroblastoma, astrocytoma, glioma, colon cancer, lung cancer, thyroid carcinoma, leukemia, erythroleukemia and multiple myeloma. Our studies revealed apoptosis induction and G2-M cell cycle arrest in Riluzole treated A549, C6 and HT-29 cells. RESULT: At the molecular level, we found that these cells treated with Riluzole had a decrease of Cyclin B and an increase of p21 Waf1/Cip1 and p53 expression. We also observed an enhancement of CDK1 and Chk2 phosphorylation. Reported changes may suggest the involvement of these proteins in G2-M arrest, observed in flow cytometry analysis. These data indicated the potential use of Riluzole in the treatment of different types of cancers.

Tumor-Associated Macrophages as Target for Antitumor Therapy.

It is well known that the microenvironment of solid tumors is rich in inflammatory cells that influence tumor growth and development. Macrophages, called tumor-associated macrophages (TAMs), are the most abundant immune cell population present in tumor tissue. Several studies have demonstrated that the density of TAMs is associated with a poor prognosis and positively correlates with tumor growth. Several studies have proved that TAMs may activate and protect tumor stem cells, stimulate their proliferation as well as promote angiogenesis and metastasis. Furthermore, TAMs-derived cytokines and other proteins, such as CCL-17, CCL-22, TGF-ß, IL-10, arginase 1, and galectin-3, make a significant contribution to immunosuppression. Since TAMs influence various aspects of cancer progression, there are many attempts to use them as a target for immunotherapy. The numerous studies have shown that the primary tumor growth and the number of metastatic sites can be significantly decreased by decreasing the population of macrophages in tumor tissue, for example, by blocking recruitment of monocytes or eliminating TAMs already present in the tumor tissue. Moreover, there are attempts at reprogramming TAMs into proinflammatory M1 macrophages or neutralizing the protumoral products of TAMs. Another approach uses TAMs for anticancer drug delivery into the tumor environment. In this review, we would like to summarize the clinical and preclinical trials that were focused on macrophages as a target for anticancer therapies.

A King Bolete, Boletus edulis (Agaricomycetes), RNA Fraction Stimulates Proliferation and Cytotoxicity of Natural Killer Cells Against Myelogenous Leukemia Cells.

Numerous studies indicate the crucial role of natural killer (NK) cells in the prevention of tumor growth and inhibition of their metastasis, which suggests the possibility of their use in cancer treatment. This therapeutic strategy required finding a selective NK cell stimulator that, upon administration, did not disturb organism homeostasis, unlike natural activators (interleukin-2 or interleukin-12). Because the majority of anticancer agents derived from Basidiomycetes are able to stimulate lymphocytes, we describe the influence of Boletus edulis RNA on a human NK cell line (NK92). Our studies showed that a B. edulis RNA fraction was not toxic against NK92 cells. Furthermore, the tested fraction significantly stimulated NK92 cell proliferation and their cytotoxicity against tumor cells. We demonstrate here, to our knowledge for the first time, that B. edulis RNA enhances NK cell activity and possesses immunomodulatory potential.

Inhibition of breast cancer metastasis by resveratrol-mediated inactivation of tumor-evoked regulatory B cells.

We reported previously that tumor-evoked regulatory B cells (tBregs) play an essential role in breast cancer lung metastasis by inducing TGF-ß-dependent conversion of metastasis-promoting Foxp3(+) regulatory T cells (Tregs). In this article, we show that resveratrol (RSV), a plant-derived polyphenol, at low and noncytotoxic doses for immune cells, can efficiently inhibit lung metastasis in mice. The mechanism of this process is that RSV inactivates Stat3, preventing the generation and function of tBregs, including expression of TGF-ß. As a result, it frees antitumor effector immune responses by disabling tBreg-induced conversion of Foxp3(+) Tregs. We propose that low doses of RSV may also benefit humans by controlling cancer escape-promoting tBregs/Tregs without nonspecific inactivation of effector immune cells.

Inhibition of lung metastasis by chemokine CCL17-mediated in vivo silencing of genes in CCR4+ Tregs.

Despite significant attractiveness of antisense oligonucleotide/RNAi technology, its clinical application has been precluded by a lack of methods for targeted delivery and transduction of primary immune cells in vivo. Here, we devised a chemokine CCL17-based strategy (TARC-arp) that transiently silences expression of genes in immune cells by delivering inhibitory oligonucleotides through their chemokine receptors. In modeling studies using mice with established 4T1.2 breast cancer, we show that IL10 produced by CCR4 cells, in particular FoxP3 regulatory T cells (Tregs), plays an important role in lung metastasis. As such, TARC-arp-mediated silencing of IL10 or FoxP3 in CCR4 Tregs is sufficient to block lung metastasis. Thus, we provide a simple solution that circumvents the problems of RNAi use in vivo, indicating that a disease outcome can be successfully controlled by delivering inhibitory oligonucleotides with chemokines to inactivate a selective subset of immune cells.

Cancer-produced metabolites of 5-lipoxygenase induce tumor-evoked regulatory B cells via peroxisome proliferator-activated receptor α.

Breast cancer cells facilitate distant metastasis through the induction of immunosuppressive regulatory B cells, designated tBregs. We report in this study that, to do this, breast cancer cells produce metabolites of the 5-lipoxygenase pathway such as leukotriene B4 to activate the peroxisome proliferator-activated receptor α (PPARα) in B cells. Inactivation of leukotriene B4 signaling or genetic deficiency of PPARα in B cells blocks the generation of tBregs and thereby abrogates lung metastasis in mice with established breast cancer. Thus, in addition to eliciting fatty acid oxidation and metabolic signals, PPARα initiates programs required for differentiation of tBregs. We propose that PPARα in B cells and/or tumor 5-lipoxygenase pathways represents new targets for pharmacological control of tBreg-mediated cancer escape.

Anti-CD20 antibody promotes cancer escape via enrichment of tumor-evoked regulatory B cells expressing low levels of CD20 and CD137L.

The possible therapeutic benefits of B-cell depletion in combating tumoral immune escape have been debated. In support of this concept, metastasis of highly aggressive 4T1 breast cancer cells in mice can be abrogated by inactivation of tumor-evoked regulatory B cells (tBreg). Here, we report the unexpected finding that B-cell depletion by CD20 antibody will greatly enhance cancer progression and metastasis. Both murine and human tBregs express low levels of CD20 and, as such, anti-CD20 mostly enriches for these cells. In the 4T1 model of murine breast cancer, this effect of enriching for tBregs suggests that B-cell depletion by anti-CD20 may not be beneficial at all in some cancers. In contrast, we show that in vivo-targeted stimulation of B cells with CXCL13-coupled CpG oligonucleotides (CpG-ODN) can block cancer metastasis by inhibiting CD20(Low) tBregs. Mechanistic investigations suggested that CpG-ODN upregulates low surface levels of 4-1BBL on tBregs to elicit granzyme B-expressing cytolytic CD8(+) T cells, offering some explanative power for the effect. These findings underscore the immunotherapeutic importance of tBreg inactivation as a strategy to enhance cancer therapy by targeting both the regulatory and activating arms of the immune system in vivo.

JAK2 mutation status, hemostatic risk factors and thrombophilic factors in essential thrombocythemia (ET) patients.

The recently discovered JAK2 V617F point mutation, found in 50-60% of ET patients, has been reported to be associated with a higher risk of thrombotic events. In this study, we explored if JAK2 V617F mutation, or coexisting thrombophilic and hemostatic risk factors, contributed to these complications. We examined 32 patients with ET, and looked for pathogenetic JAK2 V617F mutation and prothrombotic genes mutations: factor V Leiden, prothrombin and MTHFR. We also evaluated plasma levels of fibrinogen, factors VIII and XII, AT, protein C, protein S and serum level of homocysteine. Urokinase concentration was assessed in patients' plasma as well as platelet lysates. There was no difference in the number of thrombotic complications between ET patients with and without JAK2 mutation. However, we found a number of thrombophilic and hemostatic risk factors that could contribute to thrombotic complications in ET patients.

Thymic stromal lymphopoietin is a key mediator of breast cancer progression.

Inflammation is a double-edged sword that can promote or suppress cancer progression. In this study, we report that thymic stromal lymphopoietin (TSLP), an IL-7-like type 1 inflammatory cytokine that is often associated with the induction of Th2-type allergic responses in the lungs, is also expressed in human and murine cancers. Our studies with murine cancer cells indicate that TSLP plays an essential role in cancer escape, as its inactivation in cancer cells alone was sufficient to almost completely abrogate cancer progression and lung metastasis. The cancer-promoting activity of TSLP primarily required signaling through the TSLP receptor on CD4(+) T cells, promoting Th2-skewed immune responses and production of immunosuppressive factors such as IL-10 and IL-13. Expression of TSLP therefore may be a useful prognostic marker, and its targeting could have therapeutic potential.

Tumor-evoked regulatory B cells promote breast cancer metastasis by converting resting CD4⁺ T cells to T-regulatory cells.

Pulmonary metastasis of breast cancer requires recruitment and expansion of T-regulatory cells (Treg) that promote escape from host protective immune cells. However, it remains unclear precisely how tumors recruit Tregs to support metastatic growth. Here we report the mechanistic involvement of a unique and previously undescribed subset of regulatory B cells. These cells, designated tumor-evoked Bregs (tBreg), phenotypically resemble activated but poorly proliferative mature B2 cells (CD19(+) CD25(High) CD69(High)) that express constitutively active Stat3 and B7-H1(High) CD81(High) CD86(High) CD62L(Low) IgM(Int). Our studies with the mouse 4T1 model of breast cancer indicate that the primary role of tBregs in lung metastases is to induce TGF-ß-dependent conversion of FoxP3(+) Tregs from resting CD4(+) T cells. In the absence of tBregs, 4T1 tumors cannot metastasize into the lungs efficiently due to poor Treg conversion. Our findings have important clinical implications, as they suggest that tBregs must be controlled to interrupt the initiation of a key cancer-induced immunosuppressive event that is critical to support cancer metastasis.

Kynurenic acid in blood and bone marrow plasma of monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) patients.

Increased levels of kynurenic acid (KYNA) have been detected in patients with neurological, autoimmune and tumor diseases. The aim of this paper was to determine KYNA levels in the blood and bone marrow plasma of MGUS and MM patients and to find out common events which are characteristic for both pathological stages and correlates with diagnostic markers of MGUS and MM. We also examined whether bone marrow stromal cells (BMSCs) and MM cells could produce KYNA. The levels of KYNA present in plasma and in cell culture media were examined by HPLC. An increased level of KYNA was detected in the blood and marrow plasma of MGUS patients and in the blood plasma of the MM group. In the MM group, the blood KYNA level was the highest in patients with monoclonal IgG protein and with free light chains of immunoglobulins and correlated positively with blood levels of creatinine and urea. In the MGUS group, KYNA correlated positively with the C-reactive protein (CRP) level, and in both groups KYNA correlated positively with the beta2-microglobulin. We detected KYNA production in BMSCs of control and MM patients and by two myeloma cell lines used in the experiments. The results suggest that the increased KYNA level in MGUS patients was mainly caused by a dysfunction of the immune system, as it correlated positively with CRP and beta2-microglobulin levels. In MM patients, the increased KYNA level may have been a result of a dysfunction of the immune system, KYNA production by myeloma cells, and decreased KYNA excretion by kidneys.

Kynurenic acid protects against the homocysteine-induced impairment of endothelial cells.

Kynurenic acid (KYNA) is a tryptophan metabolite produced in the kynurenine pathway. In the central nervous system, KYNA exerts neuroprotective and anticonvulsant effects by mechanisms associated with its antagonist activity against the ionotropic glutamate and alpha-7 nicotinic receptors. Its presence has been documented not only in cerebrospinal fluid and brain tissue, but also in the periphery. However, KYNA's function outside the brain has not been fully elucidated. In this study, experiments performed on bovine aorta endothelial cell cultures showed for the first time that KYNA exerts a protective activity against the homocysteine-induced impairment of endothelial cells. The addition of KYNA significantly increased endothelial cell migration and proliferation, which is diminished by homocysteine. KYNA also protected cells against homocysteine-induced cytotoxicity. Our data suggest that increasing KYNA levels in blood vessels may have a significant impact on the endothelium in hyperhomocysteinemia.

Betulinic acid decreases expression of bcl-2 and cyclin D1, inhibits proliferation, migration and induces apoptosis in cancer cells.

Betulinic acid (BA) is a pentacyclic triterpene found in many plant species, among others in the bark of white birch Betula alba. BA was reported to display a wide range of biological effects, including antiviral, antiparasitic, antibacterial and anti-inflammatory activities, and in particular to inhibit growth of cancer cells. The aim of the study was further in vitro characterization of BA anticancer activity. In this study, we demonstrated a remarkable antiproliferative effect of BA in all tested tumor cell cultures including neuroblastoma, rabdomyosarcoma-medulloblastoma, glioma, thyroid, breast, lung and colon carcinoma, leukemia and multiple myeloma, as well as in primary cultures isolated from ovarian carcinoma, cervical carcinoma and glioblastoma multiforme. Furthermore, we have shown that BA decreased cancer cell motility and induced apoptotic cell death. We also observed decrease of bcl2 and cyclin D1 genes expression, and increase of bax gene expression after betulinic acid treatment. These findings demonstrate the anticancer potential of betulinic acid and suggest that it may be taken into account as a supportive agent in the treatment of cancers with different tissue origin.

Kynurenic acid in human saliva--does it influence oral microflora?

Kynurenic acid (KYNA) is an endogenous antagonist of alpha7 nicotinic receptors and all ionotropic glutamate receptors. Its neuroprotective activity has been suggested. In this study, the presence of KYNAin human saliva and its potential bactericidal role was investigated. KYNAwas found in all samples of human saliva with mean concentration of 3.4 nM. The concentration of KYNA in saliva obtained from patients with odontogenic abscesses was 3.5 times higher than in healthy subjects. We have shown that the human gingival fibroblasts produce KYNAand an inflammatory stimulant, lipopolysaccharide, enhanced its synthesis in vitro. The bactericidal effect of KYNA was also presented. We hypothesize that KYNA may contribute to the control of oral microflora.

Ammonia at pathophysiologically relevant concentrations activates kynurenic acid synthesis in cultured astrocytes and neurons.

The synthesis of the NMDA receptor glycine site antagonist kynurenic acid (KYNA) from exogenously added kynurenine was measured in cultured cerebral cortical neurons, cortical astrocytes and an oligodendroglial cell line OLN-93, incubated for 2 h in the presence or absence of ammonium acetate ("ammonia") at 0.1-10 mM concentration. In neurons ammonia stimulated KYNA synthesis to approximately 160-170% of control at 0.1-1.0mM, did not produce any effect at 2.5 and 5 mM, and inhibited the synthesis to approximately 80% of control at 10mM concentration. In astrocytes, a stimulation to approximately 200% of control occurred in the whole ammonia concentration range. No effect of ammonia was noted in OLN-93 cells. Increased KYNA synthesis may represent a cytoprotective response of astrocytes and neurons against the NMDA receptor-mediated cytotoxic activity of ammonia.

Demonstration of kynurenine aminotransferases I and II and characterization of kynurenic acid synthesis in oligodendrocyte cell line (OLN-93).

In the present study we demonstrate for the first time that both kynurenine aminotransferase (KAT) isoforms I and II are present in the permanent immature rat oligodendrocytes cell line (OLN-93). Moreover, we provide evidence that OLN-93 cells are able to synthesize kynurenic acid (KYNA) from exogenously added L-kynurenine and we characterize its regulation by extrinsic factors. KYNA production in OLN-93 cells was depressed in the presence of aminotransferase inhibitor, aminooxyacetic acid and was not affected by depolarizing agents such as 50 mM K+ and 4-aminopyridine. Glutamate agonists, L-glutamate and D,L-homocysteine significantly decreased KYNA production. Selective agonist of ionotropic glutamate receptors Amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazolepropionic acid (AMPA) lowered KYNA production in OLN-93 cell line, whereas N-methyl-D-aspartate (NMDA) had no influence on KYNA production. Furthermore, KYNA synthesis in OLN-93 cells was decreased in a concentration-dependent manner by amino acids transported by L-system, L-leucine, L-cysteine and L-tryptophan. The role of KYNA synthesis in oligodendrocytes needs further investigation.

Effect of oxidative stress on the junctional proteins of cultured cerebral endothelial cells.

(1) There is increasing evidence that the cerebral endothelium and the blood-brain barrier (BBB) plays an important role in the oxidative stress-induced brain damage. The aim of the present study was to investigate the role of interendothelial junctional proteins in the BBB permeability increase induced by oxidative stress. (2) For the experiments, we have used cultured cerebral endothelial cells exposed to hypoxia/reoxygenation or treated with the redox cycling quinone 2,3-Dimethoxy-1,4-naphthoquinone (DMNQ) in the presence or absence of glucose. The expression of junctional proteins and activation of mitogen activated protein kinases (MAPK) was followed by Western-blotting, the interaction of junctional proteins was investigated using coimmunoprecipitation. (3) Oxidative stress induces a downregulation of the tight junction protein occludin expression which is more pronounced in the absence of glucose. Furthermore, oxidative stress leads to disruption of the cadherin-beta-catenin complex and an activation of extracellular signal-regulated kinase (ERK1/2), which is more intense in the absence of glucose. (4) We have shown that one of the causes of the BBB breakdown is probably the structural alteration of the junctional complex caused by oxidative stress, a process in which ERK1/2 may play an important role.

Demonstration of kynurenine aminotransferases I and II and characterization of kynurenic acid synthesis in cultured cerebral cortical neurons.

The present study characterizes the synthesis of kynurenic acid (KYNA) from exogenously added kynurenine and its regulation by extrinsic factors, in cultured cerebral cortical neurons and, for comparison, in astrocytes incubated under identical conditions. The neuronal culture showed positive immunostaining for both kynurenic acid aminotransferase (KAT) isoforms I and II. Neurons synthesized KYNA at a rate about 2.3 times higher than astrocytes. Neuronal, but not astrocytic, KYNA synthesis was lowered approximately 30% by ionotropic glutamate receptor agonists [(R,S)-3-hydroxy-5-methoxyloxasole-4-propionic acid (AMPA; 100 microM) and N-methyl-D-aspartic acid (NMDA; 100 microM)] and depolarizing agents [KCl (50 mM) and 4-aminopyridine (4-AP; 10 microM)]. Neuronal and astrocytic synthesis alike were vulnerable to inhibition exerted by the aminotransferase inhibitor aminooxyacetic acid (AOAA), glutamate (IC50: 31 and 85 microM, respectively), substrates of the L-amino transport system [leucine (Leu); IC50: 19 and 42 microM, respectively] and 2-aminobicyclo[2,2,1]heptane-2-carboxylic acid (BCH; IC50: 19 and 28 microM, respectively). Glutamine (Gln), which is a metabolic precursor of glutamate in astrocytes and L-system substrate in both cell types, inhibited KYNA synthesis both in neurons and in astrocytes (IC50: 268 and 318 microM, respectively). alpha-Ketoisocaproic acid (KIC), a Leu transamination product that is produced mainly in astrocytes and shuttled to neurons to modulate intraneuronal concentration of glutamate, stimulated KYNA synthesis in neurons but did not affect the synthesis in astrocytes. In conclusion, this study is the first to demonstrate active, regulation-prone KYNA synthesis in neurons.