Inhibition of 125I-epidermal growth factor binding to murine fibroblasts and keratinocytes by irradiation with ultraviolet-B light

Treatment of murine Swiss 3T3 fibroblasts and XB/2 keratinocytes with UV-B light (302 nm) resulted in a dose-dependent inhibition of [125I] epidermal growth factor (EGF) binding. The light dose required to achieve 50% inhibition of binding in both cell types was 80–85 J/m2 Decreased [125I] platelet-derived growth factor binding was not evoked even by light doses of up to 280 J/m2 UV-B irradiation did not stimultate phosphorylation of the 80 kd protein substrate for protein kinase C. Furthermore, its effect on [125I]EGF binding was not altered as a consequence of protein kinase C down-regulation following prolonged exposure of cells to phorbol esters. These results indicate that UV-B-induced transmodulation of the epidermal growth factor receptor is a specific event mediated through a protein kinase C-indepen dent pathway. Transfer of culture medium from irradiated cells to untreated control cells showed this effect was not induced as a result of transforming growth factor α release and subsequent binding to the EGF receptor in these cells.

Macrophage migration inhibitory factor is up-regulated in human first-trimester placenta stimulated by soluble antigen of Toxoplasma gondii, resulting in increased monocyte adhesion on villous explants

Considering the potential role of macrophage migration inhibitory factor (MIF) in the inflammation process in placenta when infected by pathogens, we investigated the production of this cytokine in chorionic villous explants obtained from human first-trimester placentas stimulated with soluble antigen from Toxoplasma gondii (STAg). Parallel cultures were performed with villous explants stimulated with STAB, interferon-gamma (IFN-gamma), or STAB plus IFN-gamma. To assess the role of placental MIF on monocyte adhesiveness to human trophoblast, explants were co-cultured with human myelomonocytic THP-1 cells in the presence or absence of supernatant from cultures treated with STAB (SPN), SPN plus anti-MIF antibodies, or recombinant MIF. A significantly higher concentration of MIF was produced and secreted by villous explants treated with STAB or STAB plus IFN-gamma after 24-hour culture. Addition of SPN or recombinant MIF was able to increase THP-1 adhesion, which was inhibited after treatment with anti-MIF antibodies. This phenomenon was associated with intercellular adhesion molecule expression by villous explants. Considering that the processes leading to vertical dissemination of T. gondii remain widely unknown, our results demonstrate that MIF production by human first-trimester placenta is up-regulated by parasite antigen and may play an essential role as an autocrine/paracrine mediator in placental infection by T. gondii.

Endogenous Hepatocyte Growth Factor Attenuates Inflammatory Response in Glycerol-Induced Acute Kidney Injury

Background: Hepatocyte growth factor (HGF) is overexpressed after acute kidney injury (AKI). The aim of this study was to evaluate the role of endogenous HGF in the progression of the inflammatory response in glycerol-induced AKI (Gly-AKI) in rats. Methods: Renal and systemic HGF expressions were evaluated during the development of Gly-AKI. Subsequently, the blockade of endogenous HGF was analyzed in rats treated with anti-HGF antibody concomitant to glycerol injection. Apoptosis, cell infiltration and chemokine and cytokine profiles were investigated. Results: We detected an early peak of renal and plasma HGF protein expressions 3 h after glycerol injection. The pharmacological blockade of the endogenous HGF exacerbated the renal impairment, the tubular apoptosis, the renal expression of monocyte chemoattractant protein-1 and the macrophage, CD43+, CD4+ and CD8+ T lymphocytes renal infiltration. The analysis of mRNA expressions of Th1 (t-bet, TNF-alpha, IL-1 beta) and Th2 (gata-3, IL-4, IL-10) cytokines showed a Th1-polarized response in Gly-AKI rats that was aggravated with the anti-HGF treatment. Conclusion: Endogenous HGF attenuates the renal inflammatory response, leukocyte infiltration and Th1 polarization after glycerol injection. The control of cellular immune response may partly explain the protective effect of endogenous HGF in the development of Gly-AKI. Copyright (C) 2008 S. Karger AG, Basel

Inhibition of in vivo leishmanicidal mechanisms by tempol: Nitric oxide down-regulation and oxidant scavenging

Tempol (4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy) has long been known to protect experimental animals from the injury associated with oxidative and inflammatory conditions. In the latter case, a parallel decrease in tissue protein nitration levels has been observed. Protein nitration represents a shift in nitric oxide actions from physiological to pathophysiological and potentially damaging pathways involving its derived oxidants such as nitrogen dioxide and peroxynitrite. In infectious diseases, protein tyrosine nitration of tissues and cells has been taken as evidence for the involvement of nitric oxide-derived oxidants in microbicidal mechanisms. To examine whether tempol inhibits the microbicidal action of macrophages, we investigated its effects on Leishmania amazonensis infection in vitro (RAW 264.7 murine macrophages) and in vivo (C57B1/6 mice). Tempol was administered in the drinking water at 2 mM throughout the experiments and shown to reach infected footpads as the nitroxide plus the hydroxylamine derivative by EPR analysis. At the time of maximum infection (6 weeks), tempol increased footpad lesion size (120%) and parasite burden (150%). In lesion extracts, tempol decreased overall nitric oxide products and expression of inducible nitric oxide synthase to about 80% of the levels in control animals. Nitric oxide-derived products produced by radical mechanisms, such as 3-nitrotyrosine and nitrosothiol, decreased to about 40% of the levels in control mice. The results indicate that tempol worsened L. amazonensis infection by a dual mechanism involving down-regulation of iNOS expression and scavenging of nitric oxide-derived oxidants. Thus, the development of therapeutic strategies based on nitroxides should take into account the potential risk of altering host resistance to parasite infection. (c) 2008 Elsevier Inc. All rights reserved.

Granulocyte-macrophage colony-stimulating factor augments phagocytosis of mycobacterium avium complex by human immunodeficiency virus type 1-infected monocytes/macrophages in vitro and in vivo

The role of human immunodeficiency virus type 1 (HIV-1) infection on the ability of human monocytes/macrophages to phagocytose Mycobacterium avium complex (MAC) in vivo and in vitro and the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on this function were investigated. By use of a flow cytometric assay to quantify phagocytosis, HIV-1 infection was found to impair the ability of monocyte-derived macrophages to phagocytose MAC in vitro, whereas GM-CSF significantly improved this defect. Phagocytosis was not altered by exposure to a mutant form of GM-CSF (E21R) binding only to the α chain of the GM-CSF receptor, suggesting that signaling by GM-CSF that leads to augmentation of phagocytosis is via the β chain of the receptor. In a patient with AIDS and disseminated multidrug-resistant MAC infection, GM-CSF treatment improved phagocytosis of MAC by peripheral blood monocytes and reduced bacteremia. These results imply that GM-CSF therapy may be useful in restoring antimycobacterial function by human monocytes/macrophages.

Melatonin : an overlooked factor in schizophrenia and in the inhibition of anti-psychotic side effects

This paper reviews melatonin as an overlooked factor in the developmental etiology and maintenance of schizophrenia; the neuroimmune and oxidative pathophysiology of schizophrenia; specific symptoms in schizophrenia, including sleep disturbance; circadian rhythms; and side effects of antipsychotics, including tardive dyskinesia and metabolic syndrome. Electronic databases, i.e. PUBMED, Scopus and Google Scholar were used as sources for this review using keywords: schizophrenia, psychosis, tardive dyskinesia, antipsychotics, metabolic syndrome, drug side effects and melatonin. Articles were selected on the basis of relevance to the etiology, course and treatment of schizophrenia. Melatonin levels and melatonin circadian rhythm are significantly decreased in schizophrenic patients. The adjunctive use of melatonin in schizophrenia may augment the efficacy of antipsychotics through its anti-inflammatory and antioxidative effects. Further, melatonin would be expected to improve sleep disorders in schizophrenia and side effects of anti-psychotics, such as tardive dyskinesia, metaboilic syndrome and hypertension. It is proposed that melatonin also impacts on the tryptophan catabolic pathway via its effect on stress response and cortisol secretion, thereby impacting on cortex associated cognition, amygdala associated affect and striatal motivational processing. The secretion of melatonin is decreased in schizophrenia, contributing to its etiology, pathophysiology and management. Melatonin is likely to have impacts on the metabolic side effects of anti-psychotics that contribute to subsequent decreases in life-expectancy.

Short-chain fatty acids increase expression and secretion of stromal cell-derived factor-1 in mouse and human pre-adipocytes

Objective: Stromal cell-derived factor-1 (SDF-1) is expressed in pre-adipocytes but its role is unknown. We investigated butyrate (a histone deacetylase inhibitor - HDACi) and other short-chain fatty acids (SCFA) in the regulation of SDF-1. We further investigated whether effects of SCFA were signalled through G protein-coupled receptors FFA2 and FFA3. Design and Results: SDF-1 mRNA expression and protein secretion were studied in 3T3-L1 cells and human pre-adipocytes. SDF-1 was abundant, with mRNA and protein levels increased by butyrate. This was replicated with acetate and propionate, but not with trichostatin or valproate. Trichostatin inhibited SDF-1 secretion. Pertussis toxin blocked stimulation by butyrate. The order of potency of SCFA in stimulating SDF-1 (C3 > C4 > C2) is consistent with action through FFA3. Silencing the FFA3 gene abolished butyrate-stimulated SDF-1 expression and secretion. FFA3 was expressed in both pre-adipocytes and adipocytes, while FFA2 was expressed in adipocytes only. SDF-1 expression was low in murine macrophage J774.2 cells, while the SDF-1 receptor CXCR4 was absent from 3T3-L1 cells but abundant in J774.2 macrophages. In human pre-adipocytes, FFA3 was also expressed and SCFA increased SDF-1 secretion. Conclusions: SDF-1 and CXCR4 may mediate the interaction between adipose stromal cells and macrophages. Effects of SCFA are mediated through FFA3, but not histone deacetylase inhibition.

Sporothrix schenckii lipid inhibits macrophage phagocytosis: Involvement of nitric oxide and tumour necrosis factor-alpha

The role of cell-wall compounds in the immune response to sporotrichosis is unknown. The effect of cell-wall compounds and exoantigen obtained from Sporothrix schenckii in macrophage/fungus interaction was analysed with respect to nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha). The lipid compound of the cell wall plays an important role in the pathogenesis of this mycosis and was found to inhibit the phagocytic process and to induce high liberation of NO and TNF-alpha in macrophage cultures in the present study. This is a very interesting result because it is the first report about one compound of the fungus S. schenckii that presents this activity.

Protocatechuic Acid Alkyl Esters: Hydrophobicity As a Determinant Factor for Inhibition of NADPH Oxidase

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Granulocyte macrophage colony-stimulating factor enhances the modulatory effect of cytokines on monocyte-derived multinucleated giant cell formation and fungicidal activity against Paracoccidioides brasiliensis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Antigenic Activity of Bacterial Endodontic Contents from Primary Root Canal Infection with Periapical Lesions against Macrophage in the Release of Interleukin-1 beta and Tumor Necrosis Factor alpha

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Macrophage Migration Inhibitory Factor in the Paraventricular Nucleus Plays a Major Role in the Sympathoexcitatory Response to Salt

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)