RESUMO
Nitric oxide (NO) plays a key role in inflammation. It is partly produced by three forms of NOS: eNOS of inflammatory cells, nNOS of neural cells and iNOS (inducible isoform). Estrogens can cause an anti-inflammatory effect, although it is not yet clear through which NOS isoforms. The aim of this study was to evaluate the role of the different NOS isoforms, as well as estrogen receptors (ERs) α and ß, on the anti-inflammatory effects of estrogens. To avoid the influence of endogenous glucocorticoids or sexual hormones, male rats were hypophysectomized. Animals were segregated into two control groups (no-treatment control group and SHAM-operated animals) and three hypophysectomized groups (no-hormonal treatment, with estradiol-17ß, or with testosterone replacement treatment). Freund's complete adjuvant (1 mg) was administered to the footpad of all animals. Measurements were made based on footpad inflammation (with a plethysmometer) such as eNOS, nNOS, iNOS and ER α and ß protein expression (by immunohistochemistry principle/method) on days 1, 7 and 14. Only estradiol decreased inflammation, accompanied by increased levels of eNOS and nNOS and differential expression of ERs α and ß in the inflammatory infiltrate. The higher levels of estradiol-induced eNOS and nNOS ocurred perhaps through the activation of ER ß.
Assuntos
Estradiol/farmacologia , Receptor beta de Estrogênio/metabolismo , Inflamação/tratamento farmacológico , Óxido Nítrico Sintase Tipo III/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Animais , Estrogênios , Masculino , RatosRESUMO
Naegleria fowleri infects humans through the nasal mucosa causing a disease in the central nervous system known as primary amoebic meningoencephalitis (PAM). Polymorphonuclear cells (PMNs) play a critical role in the early phase of N. fowleri infection. Recently, a new biological defence mechanism called neutrophil extracellular traps (NETs) has been attracting attention. NETs are composed of nuclear DNA combined with histones and antibacterial proteins, and these structures are released from the cell to direct its antimicrobial attack. In this work, we evaluate the capacity of N. fowleri to induce the liberation of NETs by human PMN cells. Neutrophils were cocultured with unopsonized or IgG-opsonized N. fowleri trophozoites. DNA, histone, myeloperoxidase (MPO) and neutrophil elastase (NE) were stained, and the formation of NETs was evaluated by confocal microscopy and by quantifying the levels of extracellular DNA. Our results showed N. fowleri induce the liberation of NETs including release of MPO and NE by human PMN cells as exposure interaction time is increased, but N. fowleri trophozoites evaded killing. However, when trophozoites were opsonized, they were susceptible to the neutrophils activity. Therefore, our study suggests that antibody-mediated PMNs activation through NET formation may be crucial for antimicrobial responses against N. fowleri.
Assuntos
Anticorpos Antiprotozoários/imunologia , Armadilhas Extracelulares/imunologia , Imunoglobulina G/imunologia , Naegleria fowleri/imunologia , Ativação de Neutrófilo/imunologia , Neutrófilos/imunologia , Trofozoítos/imunologia , Animais , Técnicas de Cocultura , DNA/metabolismo , Histonas/metabolismo , Humanos , Elastase de Leucócito/metabolismo , Meningoencefalite/imunologia , Meningoencefalite/parasitologia , Microscopia Confocal , Mucosa Nasal/parasitologia , Peroxidase/metabolismo , Fagocitose/imunologiaRESUMO
The impact of intermittent fasting versus ad libitum feeding during Salmonella typhimurium infection was evaluated in terms of duodenum IgA levels, bacterial clearance and intestinal and extra-intestinal infection susceptibility. Mice that were intermittently fasted for 12 weeks or fed ad libitum were infected with S. typhimurium and assessed at 7 and 14 days post-infection. Next, we evaluated bacterial load in the faeces, Peyer's patches, spleen and liver by plate counting, as well as total and specific intestinal IgA and plasmatic corticosterone levels (by immunoenzymatic assay) and lamina propria IgA levels in plasma cells (by cytofluorometry). Polymeric immunoglobulin receptor, α- and J-chains, Pax-5 factor, pro-inflammatory cytokine (tumour necrosis factor-α and interferon-γ) and anti-inflammatory cytokine (transforming growth factor-ß) mRNA levels were assessed in mucosal and liver samples (by real-time PCR). Compared with the infected ad libitum mice, the intermittently fasted infected animals had (1) lower intestinal and systemic bacterial loads; (2) higher SIgA and IgA plasma cell levels; (3) higher mRNA expression of most intestinal parameters; and (4) increased or decreased corticosterone levels on day 7 and 14 post-infection, respectively. No contribution of liver IgA was observed at the intestinal level. Apparently, the changes following metabolic stress induced by intermittent fasting during food deprivation days increased the resistance to S. typhimurium infection by triggering intestinal IgA production and presumably, pathogen elimination by phagocytic inflammatory cells.
Assuntos
Duodeno/imunologia , Jejum , Imunoglobulina A/imunologia , Plasmócitos/imunologia , Infecções por Salmonella/imunologia , Salmonella typhimurium/imunologia , Estresse Fisiológico/imunologia , Animais , Carga Bacteriana , Corticosterona/sangue , Citocinas/genética , Citocinas/metabolismo , Duodeno/microbiologia , Fezes/microbiologia , Regulação da Expressão Gênica , Imunidade nas Mucosas , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Fator de Transcrição PAX5/genética , Fator de Transcrição PAX5/metabolismoRESUMO
Amoebic liver abscess (ALA) is the most important extraintestinal complication of Entamoeba histolytica infection. Amoebic liver abscess development causes severe destruction of the liver tissue concomitant with a strong inflammatory reaction. We analyse the in situ expression of TNF-α, IFN-γ, IL-1ß, 1L-8 and IL-10 at different stages of ALA development in a susceptible animal model. Results showed that after inoculation, neutrophils (PMN) and some macrophages infiltrated the liver and were positive for TNF-α and IFN-γ at the acute phase of amoeba infection. The presence of these cytokines was transient and decreased as tissue damage progressed. In contrast, IL-1ß and IL-8 were detected mainly in neutrophils and macrophages from the periods of acute infection to subacute and chronic infection and decreased when granulomas were formed. The IL-10 was expressed in PMN and mononuclear cells and only during a short period at the onset of acute infection. The qRT-PCR of mRNA revealed a relationship with the expression of the cytokines in cells found in the ALA. Furthermore, our data suggest that IL-10 does not regulate local production of these cytokines. Our results indicate that an exacerbated inflammatory milieu is established and contributes to liver tissue damage and probably supports the survival of the parasites.
Assuntos
Citocinas , Entamoeba histolytica/imunologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/imunologia , Inflamação/imunologia , Abscesso Hepático Amebiano/imunologia , Abscesso Hepático Amebiano/metabolismo , Fígado/imunologia , Fígado/metabolismo , Macrófagos/imunologia , Neutrófilos/imunologia , RNA Mensageiro/análise , Animais , Cricetinae , Citocinas/genética , Citocinas/metabolismo , Modelos Animais de Doenças , Entamoeba histolytica/metabolismo , Imuno-Histoquímica , Inflamação/metabolismo , Fígado/parasitologia , Fígado/ultraestrutura , Abscesso Hepático Amebiano/parasitologia , Macrófagos/metabolismo , Masculino , Neutrófilos/metabolismo , Reação em Cadeia da PolimeraseRESUMO
Entamoeba histolytica trophozoites were inoculated into the liver of hamsters and serum nitrate/nitrite levels [expressed as nitric oxide (NO) production] were determined at different times during amebic liver abscess (ALA) development. We also tested the effects of NO synthase (NOS) inhibitors such as N(G)-nitro-L-arginine methyl ester (L-NAME), aminoguanidine, and dexamethasone during ALA production. Since NOS activity has been correlated with expression of reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) in tissues, we performed histochemistry studies to determine the activity of the latter in livers infected with E. histolytica trophozoites. Production of NO in serum was directly proportional to the size of ALAs, and NOS inhibitors caused low levels of NO and smaller ALAs. Our data suggest that NO does not have any lytic effect on E. histolytica trophozoites and is therefore incapable of providing protection against the amebic liver infection. In addition, NADPHd activity was detected histochemically in hepatocytes and inflammatory cells associated with focal necrosis containing trophozoites. The positive reactivity observed in these parasites may be attributable to a close biochemical similarity of NADPHd to the NADPH:flavin oxidoreductase described in E. histolytica by other investigators.